CINXE.COM

<!DOCTYPE html> <html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available" lang="en" dir="ltr"> <head> <meta charset="UTF-8"> <title>H.323 - Wikipedia</title> <script>(function(){var className="client-js vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available";var cookie=document.cookie.match(/(?:^|; )enwikimwclientpreferences=([^;]+)/);if(cookie){cookie[1].split('%2C').forEach(function(pref){className=className.replace(new RegExp('(^| )'+pref.replace(/-clientpref-\w+$|[^\w-]+/g,'')+'-clientpref-\\w+( |$)'),'$1'+pref+'$2');});}document.documentElement.className=className;}());RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy", "wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"afb86b3b-c2b1-4dcd-a604-74f3a04a14cb","wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"H.323","wgTitle":"H.323","wgCurRevisionId":1214242721,"wgRevisionId":1214242721,"wgArticleId":6312116,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["CS1 maint: unfit URL","Wikipedia articles needing factual verification from March 2011","Articles with short description","Short description is different from Wikidata","Articles lacking in-text citations from April 2020","All articles lacking in-text citations","Wikipedia articles in need of updating from June 2021","All Wikipedia articles in need of updating","Articles with multiple maintenance issues","All articles with unsourced statements","Articles with unsourced statements from June 2008", "Articles with unsourced statements from March 2009","VoIP protocols","Videotelephony","ITU-T recommendations","ITU-T H Series Recommendations"],"wgPageViewLanguage":"en","wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName":"H.323","wgRelevantArticleId":6312116,"wgIsProbablyEditable":true,"wgRelevantPageIsProbablyEditable":true,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgNoticeProject":"wikipedia","wgCiteReferencePreviewsActive":false,"wgFlaggedRevsParams":{"tags":{"status":{"levels":1}}},"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":0,"wgVisualEditor":{"pageLanguageCode":"en","pageLanguageDir":"ltr","pageVariantFallbacks":"en"},"wgMFDisplayWikibaseDescriptions":{"search":true,"watchlist":true,"tagline":false,"nearby":true},"wgWMESchemaEditAttemptStepOversample":false,"wgWMEPageLength":30000,"wgRelatedArticlesCompat":[],"wgCentralAuthMobileDomain":false,"wgEditSubmitButtonLabelPublish":true,"wgULSPosition": "interlanguage","wgULSisCompactLinksEnabled":false,"wgVector2022LanguageInHeader":true,"wgULSisLanguageSelectorEmpty":false,"wgWikibaseItemId":"Q1128649","wgCheckUserClientHintsHeadersJsApi":["brands","architecture","bitness","fullVersionList","mobile","model","platform","platformVersion"],"GEHomepageSuggestedEditsEnableTopics":true,"wgGETopicsMatchModeEnabled":false,"wgGEStructuredTaskRejectionReasonTextInputEnabled":false,"wgGELevelingUpEnabledForUser":false};RLSTATE={"ext.globalCssJs.user.styles":"ready","site.styles":"ready","user.styles":"ready","ext.globalCssJs.user":"ready","user":"ready","user.options":"loading","ext.cite.styles":"ready","skins.vector.search.codex.styles":"ready","skins.vector.styles":"ready","skins.vector.icons":"ready","jquery.makeCollapsible.styles":"ready","ext.wikimediamessages.styles":"ready","ext.visualEditor.desktopArticleTarget.noscript":"ready","ext.uls.interlanguage":"ready","wikibase.client.init":"ready","ext.wikimediaBadges":"ready"};RLPAGEMODULES= ["ext.cite.ux-enhancements","mediawiki.page.media","site","mediawiki.page.ready","jquery.makeCollapsible","mediawiki.toc","skins.vector.js","ext.centralNotice.geoIP","ext.centralNotice.startUp","ext.gadget.ReferenceTooltips","ext.gadget.switcher","ext.urlShortener.toolbar","ext.centralauth.centralautologin","mmv.bootstrap","ext.popups","ext.visualEditor.desktopArticleTarget.init","ext.visualEditor.targetLoader","ext.echo.centralauth","ext.eventLogging","ext.wikimediaEvents","ext.navigationTiming","ext.uls.interface","ext.cx.eventlogging.campaigns","ext.cx.uls.quick.actions","wikibase.client.vector-2022","ext.checkUser.clientHints","ext.growthExperiments.SuggestedEditSession","wikibase.sidebar.tracking"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.impl(function(){return["user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"}); }];});});</script> <link rel="stylesheet" href="/w/load.php?lang=en&modules=ext.cite.styles%7Cext.uls.interlanguage%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediaBadges%7Cext.wikimediamessages.styles%7Cjquery.makeCollapsible.styles%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init&only=styles&skin=vector-2022"> <script async="" src="/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022"></script> <meta name="ResourceLoaderDynamicStyles" content=""> <link rel="stylesheet" href="/w/load.php?lang=en&modules=site.styles&only=styles&skin=vector-2022"> <meta name="generator" content="MediaWiki 1.44.0-wmf.4"> <meta name="referrer" content="origin"> <meta name="referrer" content="origin-when-cross-origin"> <meta name="robots" content="max-image-preview:standard"> <meta name="format-detection" content="telephone=no"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/d/d1/H323_1gk.gif"> <meta property="og:image:width" content="1200"> <meta property="og:image:height" content="897"> <meta property="og:image" content="https://upload.wikimedia.org/wikipedia/commons/d/d1/H323_1gk.gif"> <meta property="og:image:width" content="800"> <meta property="og:image:height" content="598"> <meta property="og:image:width" content="640"> <meta property="og:image:height" content="478"> <meta name="viewport" content="width=1120"> <meta property="og:title" content="H.323 - Wikipedia"> <meta property="og:type" content="website"> <link rel="preconnect" href="//upload.wikimedia.org"> <link rel="alternate" media="only screen and (max-width: 640px)" href="//en.m.wikipedia.org/wiki/H.323"> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=H.323&action=edit"> <link rel="apple-touch-icon" href="/static/apple-touch/wikipedia.png"> <link rel="icon" href="/static/favicon/wikipedia.ico"> <link rel="search" type="application/opensearchdescription+xml" href="/w/rest.php/v1/search" title="Wikipedia (en)"> <link rel="EditURI" type="application/rsd+xml" href="//en.wikipedia.org/w/api.php?action=rsd"> <link rel="canonical" href="https://en.wikipedia.org/wiki/H.323"> <link rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en"> <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" href="/w/index.php?title=Special:RecentChanges&feed=atom"> <link rel="dns-prefetch" href="//meta.wikimedia.org" /> <link rel="dns-prefetch" href="//login.wikimedia.org"> </head> <body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject mw-editable page-H_323 rootpage-H_323 skin-vector-2022 action-view"><a class="mw-jump-link" href="#bodyContent">Jump to content</a> <div class="vector-header-container"> <header class="vector-header mw-header"> <div class="vector-header-start"> <nav class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-dropdown" class="vector-dropdown vector-main-menu-dropdown vector-button-flush-left vector-button-flush-right" > <input type="checkbox" id="vector-main-menu-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-main-menu-dropdown" class="vector-dropdown-checkbox " aria-label="Main menu" > <label id="vector-main-menu-dropdown-label" for="vector-main-menu-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-menu mw-ui-icon-wikimedia-menu"></span> <span class="vector-dropdown-label-text">Main menu</span> </label> <div class="vector-dropdown-content"> <div id="vector-main-menu-unpinned-container" class="vector-unpinned-container"> <div id="vector-main-menu" class="vector-main-menu vector-pinnable-element"> <div class="vector-pinnable-header vector-main-menu-pinnable-header vector-pinnable-header-unpinned" data-feature-name="main-menu-pinned" data-pinnable-element-id="vector-main-menu" data-pinned-container-id="vector-main-menu-pinned-container" data-unpinned-container-id="vector-main-menu-unpinned-container" > <div class="vector-pinnable-header-label">Main menu</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-main-menu.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-main-menu.unpin">hide</button> </div> <div id="p-navigation" class="vector-menu mw-portlet mw-portlet-navigation" > <div class="vector-menu-heading"> Navigation </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-mainpage-description" class="mw-list-item"><a href="/wiki/Main_Page" title="Visit the main page [z]" accesskey="z"><span>Main page</span></a></li><li id="n-contents" class="mw-list-item"><a href="/wiki/Wikipedia:Contents" title="Guides to browsing Wikipedia"><span>Contents</span></a></li><li id="n-currentevents" class="mw-list-item"><a href="/wiki/Portal:Current_events" title="Articles related to current events"><span>Current events</span></a></li><li id="n-randompage" class="mw-list-item"><a href="/wiki/Special:Random" title="Visit a randomly selected article [x]" accesskey="x"><span>Random article</span></a></li><li id="n-aboutsite" class="mw-list-item"><a href="/wiki/Wikipedia:About" title="Learn about Wikipedia and how it works"><span>About Wikipedia</span></a></li><li id="n-contactpage" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us" title="How to contact Wikipedia"><span>Contact us</span></a></li> </ul> </div> </div> <div id="p-interaction" class="vector-menu mw-portlet mw-portlet-interaction" > <div class="vector-menu-heading"> Contribute </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-help" class="mw-list-item"><a href="/wiki/Help:Contents" title="Guidance on how to use and edit Wikipedia"><span>Help</span></a></li><li id="n-introduction" class="mw-list-item"><a href="/wiki/Help:Introduction" title="Learn how to edit Wikipedia"><span>Learn to edit</span></a></li><li id="n-portal" class="mw-list-item"><a href="/wiki/Wikipedia:Community_portal" title="The hub for editors"><span>Community portal</span></a></li><li id="n-recentchanges" class="mw-list-item"><a href="/wiki/Special:RecentChanges" title="A list of recent changes to Wikipedia [r]" accesskey="r"><span>Recent changes</span></a></li><li id="n-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_upload_wizard" title="Add images or other media for use on Wikipedia"><span>Upload file</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> <a href="/wiki/Main_Page" class="mw-logo"> <img class="mw-logo-icon" src="/static/images/icons/wikipedia.png" alt="" aria-hidden="true" height="50" width="50"> <span class="mw-logo-container skin-invert"> <img class="mw-logo-wordmark" alt="Wikipedia" src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" style="width: 7.5em; height: 1.125em;"> <img class="mw-logo-tagline" alt="The Free Encyclopedia" src="/static/images/mobile/copyright/wikipedia-tagline-en.svg" width="117" height="13" style="width: 7.3125em; height: 0.8125em;"> </span> </a> </div> <div class="vector-header-end"> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-collapses vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <a href="/wiki/Special:Search" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only search-toggle" title="Search Wikipedia [f]" accesskey="f"><span class="vector-icon mw-ui-icon-search mw-ui-icon-wikimedia-search"></span> <span>Search</span> </a> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail cdx-typeahead-search--auto-expand-width"> <form action="/w/index.php" id="searchform" class="cdx-search-input cdx-search-input--has-end-button"> <div id="simpleSearch" class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia" aria-label="Search Wikipedia" autocapitalize="sentences" title="Search Wikipedia [f]" accesskey="f" id="searchInput" > <span class="cdx-text-input__icon cdx-text-input__start-icon"></span> </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <nav class="vector-user-links vector-user-links-wide" aria-label="Personal tools"> <div class="vector-user-links-main"> <div id="p-vector-user-menu-preferences" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-userpage" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-dropdown" class="vector-dropdown " title="Change the appearance of the page's font size, width, and color" > <input type="checkbox" id="vector-appearance-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-appearance-dropdown" class="vector-dropdown-checkbox " aria-label="Appearance" > <label id="vector-appearance-dropdown-label" for="vector-appearance-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-appearance mw-ui-icon-wikimedia-appearance"></span> <span class="vector-dropdown-label-text">Appearance</span> </label> <div class="vector-dropdown-content"> <div id="vector-appearance-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div id="p-vector-user-menu-notifications" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=H.323" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=H.323" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o" class=""><span>Log in</span></a> </li> </ul> </div> </div> </div> <div id="vector-user-links-dropdown" class="vector-dropdown vector-user-menu vector-button-flush-right vector-user-menu-logged-out" title="Log in and more options" > <input type="checkbox" id="vector-user-links-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-user-links-dropdown" class="vector-dropdown-checkbox " aria-label="Personal tools" > <label id="vector-user-links-dropdown-label" for="vector-user-links-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-ellipsis mw-ui-icon-wikimedia-ellipsis"></span> <span class="vector-dropdown-label-text">Personal tools</span> </label> <div class="vector-dropdown-content"> <div id="p-personal" class="vector-menu mw-portlet mw-portlet-personal user-links-collapsible-item" title="User menu" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport" class="user-links-collapsible-item mw-list-item"><a href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en"><span>Donate</span></a></li><li id="pt-createaccount" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:CreateAccount&returnto=H.323" title="You are encouraged to create an account and log in; however, it is not mandatory"><span class="vector-icon mw-ui-icon-userAdd mw-ui-icon-wikimedia-userAdd"></span> <span>Create account</span></a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:UserLogin&returnto=H.323" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Log in</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pages for logged out editors <a href="/wiki/Help:Introduction" aria-label="Learn more about editing"><span>learn more</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Special:MyContributions" title="A list of edits made from this IP address [y]" accesskey="y"><span>Contributions</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Special:MyTalk" title="Discussion about edits from this IP address [n]" accesskey="n"><span>Talk</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Protocols" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Protocols"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Protocols</span> </div> </a> <ul id="toc-Protocols-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Codecs" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Codecs"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Codecs</span> </div> </a> <ul id="toc-Codecs-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Architecture" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Architecture"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Architecture</span> </div> </a> <button aria-controls="toc-Architecture-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Architecture subsection</span> </button> <ul id="toc-Architecture-sublist" class="vector-toc-list"> <li id="toc-H.323_network_elements" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#H.323_network_elements"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>H.323 network elements</span> </div> </a> <ul id="toc-H.323_network_elements-sublist" class="vector-toc-list"> <li id="toc-Terminals" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Terminals"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.1</span> <span>Terminals</span> </div> </a> <ul id="toc-Terminals-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Multipoint_control_units" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Multipoint_control_units"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.2</span> <span>Multipoint control units</span> </div> </a> <ul id="toc-Multipoint_control_units-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Gateways" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Gateways"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.3</span> <span>Gateways</span> </div> </a> <ul id="toc-Gateways-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Gatekeepers" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Gatekeepers"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.4</span> <span>Gatekeepers</span> </div> </a> <ul id="toc-Gatekeepers-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Border_elements_and_peer_elements" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Border_elements_and_peer_elements"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.5</span> <span>Border elements and peer elements</span> </div> </a> <ul id="toc-Border_elements_and_peer_elements-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-H.323_network_signaling" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#H.323_network_signaling"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>H.323 network signaling</span> </div> </a> <ul id="toc-H.323_network_signaling-sublist" class="vector-toc-list"> <li id="toc-H.225.0_call_signaling" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#H.225.0_call_signaling"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.1</span> <span>H.225.0 call signaling</span> </div> </a> <ul id="toc-H.225.0_call_signaling-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-RAS_signaling" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#RAS_signaling"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.2</span> <span>RAS signaling</span> </div> </a> <ul id="toc-RAS_signaling-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-H.245_call_control" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#H.245_call_control"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.3</span> <span>H.245 call control</span> </div> </a> <ul id="toc-H.245_call_control-sublist" class="vector-toc-list"> <li id="toc-Capability_negotiation" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Capability_negotiation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.3.1</span> <span>Capability negotiation</span> </div> </a> <ul id="toc-Capability_negotiation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Master/slave_determination" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Master/slave_determination"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.3.2</span> <span>Master/slave determination</span> </div> </a> <ul id="toc-Master/slave_determination-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Logical_channel_signaling" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Logical_channel_signaling"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.3.3</span> <span>Logical channel signaling</span> </div> </a> <ul id="toc-Logical_channel_signaling-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Fast_connect" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Fast_connect"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2.3.4</span> <span>Fast connect</span> </div> </a> <ul id="toc-Fast_connect-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> </ul> </li> <li id="toc-Use_cases" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Use_cases"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Use cases</span> </div> </a> <button aria-controls="toc-Use_cases-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Use cases subsection</span> </button> <ul id="toc-Use_cases-sublist" class="vector-toc-list"> <li id="toc-H.323_and_voice_over_IP_services" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#H.323_and_voice_over_IP_services"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>H.323 and voice over IP services</span> </div> </a> <ul id="toc-H.323_and_voice_over_IP_services-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-H.323_and_videoconference_services" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#H.323_and_videoconference_services"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.2</span> <span>H.323 and videoconference services</span> </div> </a> <ul id="toc-H.323_and_videoconference_services-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Alternatives" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Alternatives"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Alternatives</span> </div> </a> <ul id="toc-Alternatives-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">H.323</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 22 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-22" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">22 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/H.323" title="H.323 – Bulgarian" lang="bg" hreflang="bg" data-title="H.323" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/H.323" title="H.323 – Catalan" lang="ca" hreflang="ca" data-title="H.323" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/H.323" title="H.323 – Czech" lang="cs" hreflang="cs" data-title="H.323" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/H.323" title="H.323 – German" lang="de" hreflang="de" data-title="H.323" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/H.323" title="H.323 – Greek" lang="el" hreflang="el" data-title="H.323" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/H.323" title="H.323 – Spanish" lang="es" hreflang="es" data-title="H.323" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/H.323" title="H.323 – Basque" lang="eu" hreflang="eu" data-title="H.323" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/H.323" title="H.323 – French" lang="fr" hreflang="fr" data-title="H.323" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/H.323" title="H.323 – Korean" lang="ko" hreflang="ko" data-title="H.323" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/H.323" title="H.323 – Italian" lang="it" hreflang="it" data-title="H.323" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%8E%E0%B4%9A%E0%B5%8D%E0%B4%9A%E0%B5%8D._323" title="എച്ച്. 323 – Malayalam" lang="ml" hreflang="ml" data-title="എച്ച്. 323" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/H.323" title="H.323 – Dutch" lang="nl" hreflang="nl" data-title="H.323" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/H.323" title="H.323 – Japanese" lang="ja" hreflang="ja" data-title="H.323" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/H.323" title="H.323 – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="H.323" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/H.323" title="H.323 – Polish" lang="pl" hreflang="pl" data-title="H.323" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/H.323" title="H.323 – Portuguese" lang="pt" hreflang="pt" data-title="H.323" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/H.323" title="H.323 – Romanian" lang="ro" hreflang="ro" data-title="H.323" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/H.323" title="H.323 – Russian" lang="ru" hreflang="ru" data-title="H.323" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/H.323" title="H.323 – Finnish" lang="fi" hreflang="fi" data-title="H.323" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/H.323" title="H.323 – Swedish" lang="sv" hreflang="sv" data-title="H.323" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/H.323" title="H.323 – Ukrainian" lang="uk" hreflang="uk" data-title="H.323" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/H.323" title="H.323 – Chinese" lang="zh" hreflang="zh" data-title="H.323" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1128649#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/H.323" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:H.323" rel="discussion" title="Discuss improvements to the content page [t]" accesskey="t"><span>Talk</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Change language variant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">English</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Views"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/H.323"><span>Read</span></a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=H.323&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=H.323&action=history" title="Past revisions of this page [h]" accesskey="h"><span>View history</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Tools" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Tools</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Tools</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">hide</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="More options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/H.323"><span>Read</span></a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=H.323&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=H.323&action=history"><span>View history</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/H.323" title="List of all English Wikipedia pages containing links to this page [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/H.323" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u"><span>Upload file</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=H.323&oldid=1214242721" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=H.323&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=H.323&id=1214242721&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FH.323"><span>Get shortened URL</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FH.323"><span>Download QR code</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=H.323&action=show-download-screen" title="Download this page as a PDF file"><span>Download as PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=H.323&printable=yes" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1128649" title="Structured data on this page hosted by Wikidata [g]" accesskey="g"><span>Wikidata item</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Audio-visual communication signaling protocol</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><style data-mw-deduplicate="TemplateStyles:r1248332772">.mw-parser-output .multiple-issues-text{width:95%;margin:0.2em 0}.mw-parser-output .multiple-issues-text>.mw-collapsible-content{margin-top:0.3em}.mw-parser-output .compact-ambox .ambox{border:none;border-collapse:collapse;background-color:transparent;margin:0 0 0 1.6em!important;padding:0!important;width:auto;display:block}body.mediawiki .mw-parser-output .compact-ambox .ambox.mbox-small-left{font-size:100%;width:auto;margin:0}.mw-parser-output .compact-ambox .ambox .mbox-text{padding:0!important;margin:0!important}.mw-parser-output .compact-ambox .ambox .mbox-text-span{display:list-item;line-height:1.5em;list-style-type:disc}body.skin-minerva .mw-parser-output .multiple-issues-text>.mw-collapsible-toggle,.mw-parser-output .compact-ambox .ambox .mbox-image,.mw-parser-output .compact-ambox .ambox .mbox-imageright,.mw-parser-output .compact-ambox .ambox .mbox-empty-cell,.mw-parser-output .compact-ambox .hide-when-compact{display:none}</style><table class="box-Multiple_issues plainlinks metadata ambox ambox-content ambox-multiple_issues compact-ambox" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/40px-Ambox_important.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/60px-Ambox_important.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/b/b4/Ambox_important.svg/80px-Ambox_important.svg.png 2x" data-file-width="40" data-file-height="40" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span"><div class="multiple-issues-text mw-collapsible"><b>This article has multiple issues.</b> Please help <b><a href="/wiki/Special:EditPage/H.323" title="Special:EditPage/H.323">improve it</a></b> or discuss these issues on the <b><a href="/wiki/Talk:H.323" title="Talk:H.323">talk page</a></b>. <small><i>(<a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove these messages</a>)</i></small> <div class="mw-collapsible-content"> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_footnotes_needed plainlinks metadata ambox ambox-style ambox-More_footnotes_needed" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/40px-Text_document_with_red_question_mark.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/60px-Text_document_with_red_question_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/80px-Text_document_with_red_question_mark.svg.png 2x" data-file-width="48" data-file-height="48" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article includes a list of <a href="/wiki/Wikipedia:Citing_sources#General_references" title="Wikipedia:Citing sources">general references</a>, but <b>it lacks sufficient corresponding <a href="/wiki/Wikipedia:Citing_sources#Inline_citations" title="Wikipedia:Citing sources">inline citations</a></b>.<span class="hide-when-compact"> Please help to <a href="/wiki/Wikipedia:WikiProject_Reliability" title="Wikipedia:WikiProject Reliability">improve</a> this article by <a href="/wiki/Wikipedia:When_to_cite" title="Wikipedia:When to cite">introducing</a> more precise citations.</span> <span class="date-container"><i>(<span class="date">April 2020</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-Update plainlinks metadata ambox ambox-content ambox-Update" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/5/53/Ambox_current_red_Americas.svg/42px-Ambox_current_red_Americas.svg.png" decoding="async" width="42" height="34" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/53/Ambox_current_red_Americas.svg/63px-Ambox_current_red_Americas.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/53/Ambox_current_red_Americas.svg/84px-Ambox_current_red_Americas.svg.png 2x" data-file-width="360" data-file-height="290" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article needs to be <b>updated</b>.<span class="hide-when-compact"> Please help update this article to reflect recent events or newly available information.</span> <span class="date-container"><i>(<span class="date">June 2021</span>)</i></span></div></td></tr></tbody></table> </div> </div><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox hproduct"><caption class="infobox-title fn">H.323</caption><tbody><tr><td colspan="2" class="infobox-subheader">Packet-based multimedia communications systems</td></tr><tr><td colspan="2" class="infobox-image"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:H323_1gk.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d1/H323_1gk.gif/220px-H323_1gk.gif" decoding="async" width="220" height="164" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/d/d1/H323_1gk.gif 1.5x" data-file-width="265" data-file-height="198" /></a></span></td></tr><tr><th scope="row" class="infobox-label">Status</th><td class="infobox-data">In force</td></tr><tr><th scope="row" class="infobox-label">Year started</th><td class="infobox-data">1996<span class="noprint">; 28 years ago</span><span style="display:none"> (<span class="bday dtstart published updated">1996</span>)</span></td></tr><tr><th scope="row" class="infobox-label">Latest version</th><td class="infobox-data">8<br />March 2022<span class="noprint">; 2 years ago</span><span style="display:none"> (<span class="bday dtstart published updated">2022-03</span>)</span></td></tr><tr><th scope="row" class="infobox-label">Organization</th><td class="infobox-data"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a></td></tr><tr><th scope="row" class="infobox-label">Related standards</th><td class="infobox-data"><a href="/wiki/Q.931" title="Q.931">Q.931</a></td></tr><tr><th scope="row" class="infobox-label">Website</th><td class="infobox-data"><span class="url"><a rel="nofollow" class="external text" href="https://www.itu.int/rec/T-REC-H.323">www<wbr />.itu<wbr />.int<wbr />/rec<wbr />/T-REC-H<wbr />.323</a></span></td></tr></tbody></table> <p><b>H.323</b> is a recommendation from the <a href="/wiki/ITU-T" title="ITU-T">ITU Telecommunication Standardization Sector (ITU-T)</a> that defines the protocols to provide <a href="/wiki/Audio-visual" class="mw-redirect" title="Audio-visual">audio-visual</a> communication sessions on any <a href="/wiki/Packet_network" class="mw-redirect" title="Packet network">packet network</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The H.323 standard addresses call signaling and control, multimedia transport and control, and bandwidth control for point-to-point and multi-point conferences.<sup id="cite_ref-Davidson_2-0" class="reference"><a href="#cite_note-Davidson-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>It is widely implemented<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> by voice and <a href="/wiki/Videoconferencing" class="mw-redirect" title="Videoconferencing">videoconferencing</a> equipment manufacturers, is used within various <a href="/wiki/Internet" title="Internet">Internet</a> real-time applications such as <a href="/wiki/GnuGK" class="mw-redirect" title="GnuGK">GnuGK</a> and <a href="/wiki/NetMeeting" class="mw-redirect" title="NetMeeting">NetMeeting</a> and is widely deployed worldwide by service providers and enterprises for both voice and <a href="/wiki/Video" title="Video">video</a> services over <a href="/wiki/Internet_Protocol" title="Internet Protocol">IP</a> networks. </p><p>It is a part of the ITU-T H.32x series of protocols, which also address <a href="/wiki/Multimedia" title="Multimedia">multimedia</a> communications over <a href="/wiki/Integrated_Services_Digital_Network" class="mw-redirect" title="Integrated Services Digital Network">ISDN</a>, the <a href="/wiki/Public_switched_telephone_network" title="Public switched telephone network">PSTN</a> or <a href="/wiki/Signaling_System_7" class="mw-redirect" title="Signaling System 7">SS7</a>, and <a href="/wiki/3G" title="3G">3G</a> <a href="/wiki/Mobile_network" class="mw-redirect" title="Mobile network">mobile networks</a>. </p><p>H.323 call signaling is based on the ITU-T Recommendation <a href="/wiki/Q.931" title="Q.931">Q.931</a> protocol and is suited for transmitting calls across networks using a mixture of IP, PSTN, ISDN, and <a href="/wiki/QSIG" title="QSIG">QSIG</a> over ISDN. A call model, similar to the ISDN call model, eases the introduction of <a href="/wiki/IP_telephony" class="mw-redirect" title="IP telephony">IP telephony</a> into existing networks of ISDN-based <a href="/wiki/Private_branch_exchange" class="mw-redirect" title="Private branch exchange">PBX</a> systems, including transitions to IP-based PBXs. </p><p>Within the context of H.323, an IP-based PBX might be a <a href="/wiki/H.323_Gatekeeper" title="H.323 Gatekeeper">gatekeeper</a> or other call control element which provides service to <a href="/wiki/Telephone" title="Telephone">telephones</a> or <a href="/wiki/Videophone" class="mw-redirect" title="Videophone">videophones</a>. Such a device may provide or facilitate both basic services and supplementary services, such as <a href="/wiki/Call_transfer" title="Call transfer">call transfer</a>, <a href="/wiki/Call_parking" title="Call parking">park</a>, <a href="/wiki/Call_pickup" title="Call pickup">pick-up</a>, and <a href="/wiki/Hold_(telephone)" title="Hold (telephone)">hold</a>. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The first version of H.323 was published by the <a href="/wiki/ITU" class="mw-redirect" title="ITU">ITU</a> in November 1996<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> with an emphasis of enabling videoconferencing capabilities over a <a href="/wiki/Local_area_network" title="Local area network">local area network</a> (LAN), but was quickly adopted by the industry as a means of transmitting voice communication over a variety of IP networks, including <a href="/wiki/Wide_area_network" title="Wide area network">WANs</a> and the Internet (see <a href="/wiki/Voice_over_IP" title="Voice over IP">VoIP</a>). </p><p>Over the years, H.323 has been revised and re-published with enhancements necessary to better enable both voice and video functionality over <a href="/wiki/Packet-switched_network" class="mw-redirect" title="Packet-switched network">packet-switched networks</a>, with each version being <a href="/wiki/Backward-compatible" class="mw-redirect" title="Backward-compatible">backward-compatible</a> with the previous version.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Recognizing that H.323 was being used for communication not only on LANs, but over WANs and within large carrier networks, the title of H.323 was changed when published in 1998.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The title, which has since remained unchanged, is "Packet-Based Multimedia Communications Systems." The current version of H.323 was approved in 2009.<sup id="cite_ref-h323-12-2009_7-0" class="reference"><a href="#cite_note-h323-12-2009-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>One strength of H.323 was the relatively early availability of a set of standards not only defining the basic call model, but also the supplementary services needed to address business communication expectations.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2008)">citation needed</span></a></i>]</sup> </p><p>H.323 was the first VoIP standard to adopt the <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force</a> (IETF) standard <a href="/wiki/Real-time_Transport_Protocol" title="Real-time Transport Protocol">Real-time Transport Protocol</a> (RTP) to transport <a href="/wiki/Sound" title="Sound">audio</a> and video over IP networks.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2008)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Protocols">Protocols</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=2" title="Edit section: Protocols"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>H.323 is a system specification that describes the use of several ITU-T and IETF protocols. The protocols that comprise the core of almost any H.323 system are:<sup id="cite_ref-itulist_8-0" class="reference"><a href="#cite_note-itulist-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <ul><li><a href="/wiki/H.225.0" class="mw-redirect" title="H.225.0">H.225.0</a> <a href="/wiki/Registration,_Admission_and_Status" class="mw-redirect" title="Registration, Admission and Status">Registration, Admission and Status</a> (RAS), which is used between an H.323 endpoint and a Gatekeeper to provide address resolution and admission control services.</li> <li><a href="/wiki/H.225.0" class="mw-redirect" title="H.225.0">H.225.0</a> Call Signaling, which is used between any two H.323 entities in order to establish communication. (Based on <a href="/wiki/Q.931" title="Q.931">Q.931</a>)</li> <li><a href="/wiki/H.245" title="H.245">H.245</a> control protocol for multimedia communication, which describes the messages and procedures used for capability exchange, opening and closing logical channels for audio, video and data, control and indications.</li> <li><a href="/wiki/Real-time_Transport_Protocol" title="Real-time Transport Protocol">Real-time Transport Protocol</a> (RTP), which is used for sending or receiving multimedia information (voice, video, or text) between any two entities.</li></ul> <p>Many H.323 systems also implement other protocols that are defined in various <a href="/wiki/Category:ITU-T_recommendations" title="Category:ITU-T recommendations">ITU-T Recommendations</a> to provide supplementary services support or deliver other functionality to the user. Some of those Recommendations are:<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2009)">citation needed</span></a></i>]</sup> </p> <ul><li><a href="/wiki/H.235" title="H.235">H.235</a> series describes security within H.323, including security for both signaling and media.</li> <li><a href="/wiki/H.239" title="H.239">H.239</a> describes dual stream use in videoconferencing, usually one for live video, the other for still images.</li> <li><a href="/wiki/H.450" title="H.450">H.450</a> series describes various supplementary services.</li> <li><a href="/wiki/H.460" title="H.460">H.460</a> series defines optional extensions that might be implemented by an endpoint or a Gatekeeper, including ITU-T Recommendations <a href="/w/index.php?title=H.460.17&action=edit&redlink=1" class="new" title="H.460.17 (page does not exist)">H.460.17</a>, <a href="/w/index.php?title=H.460.18&action=edit&redlink=1" class="new" title="H.460.18 (page does not exist)">H.460.18</a>, and <a href="/w/index.php?title=H.460.19&action=edit&redlink=1" class="new" title="H.460.19 (page does not exist)">H.460.19</a> for <a href="/wiki/Network_address_translation" title="Network address translation">Network address translation</a> (NAT) / <a href="/wiki/Firewall_(computing)" title="Firewall (computing)">Firewall</a> (FW) traversal.</li></ul> <p>In addition to those ITU-T Recommendations, H.323 implements various IETF <a href="/wiki/Request_for_Comments" title="Request for Comments">Request for Comments</a> (RFCs) for media transport and media packetization, including the <a href="/wiki/Real-time_Transport_Protocol" title="Real-time Transport Protocol">Real-time Transport Protocol</a> (RTP). </p> <div class="mw-heading mw-heading2"><h2 id="Codecs">Codecs</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=3" title="Edit section: Codecs"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>H.323 utilizes both ITU-defined <a href="/wiki/Codec" title="Codec">codecs</a> and codecs defined outside the ITU. Codecs that are widely implemented by H.323 equipment include: </p> <ul><li><a href="/wiki/Audio_codecs" class="mw-redirect" title="Audio codecs">Audio codecs</a>: <a href="/wiki/G.711" title="G.711">G.711</a>, <a href="/wiki/G.729" title="G.729">G.729</a> (including <a href="/wiki/G.729a" class="mw-redirect" title="G.729a">G.729a</a>), <a href="/wiki/G.723.1" title="G.723.1">G.723.1</a>, <a href="/wiki/G.726" title="G.726">G.726</a>, <a href="/wiki/G.722" title="G.722">G.722</a>, <a href="/wiki/G.728" title="G.728">G.728</a>, <a href="/wiki/Speex" title="Speex">Speex</a>, <a href="/wiki/AAC-LD" title="AAC-LD">AAC-LD</a></li> <li>Text codecs: <a href="/wiki/Text_over_IP" title="Text over IP">T.140</a></li> <li><a href="/wiki/Video_codecs" class="mw-redirect" title="Video codecs">Video codecs</a>: <a href="/wiki/H.261" title="H.261">H.261</a>, <a href="/wiki/H.263" title="H.263">H.263</a>, <a href="/wiki/H.264" class="mw-redirect" title="H.264">H.264</a>, <a href="/wiki/H.265" class="mw-redirect" title="H.265">H.265</a></li></ul> <p>All H.323 terminals providing video communications shall be capable of encoding and decoding video according to H.261 <a href="/wiki/QCIF" class="mw-redirect" title="QCIF">QCIF</a>. All H.323 terminals shall have an audio codec and shall be capable of encoding and decoding speech according to ITU-T Rec. G.711. All terminals shall be capable of transmitting and receiving <a href="/wiki/A-law" class="mw-redirect" title="A-law">A-law</a> and <a href="/wiki/%CE%9C-law" class="mw-redirect" title="Μ-law">μ-law</a>. Support for other audio and video codecs is optional.<sup id="cite_ref-h323-12-2009_7-1" class="reference"><a href="#cite_note-h323-12-2009-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Architecture">Architecture</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=4" title="Edit section: Architecture"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The H.323 system defines several network elements that work together in order to deliver rich multimedia communication capabilities. Those elements are Terminals, <a href="/wiki/Multipoint_Control_Unit" class="mw-redirect" title="Multipoint Control Unit">Multipoint Control Units</a> (MCUs), <a href="/wiki/Gateway_(telecommunications)" title="Gateway (telecommunications)">Gateways</a>, Gatekeepers, and Border Elements. Collectively, terminals, multipoint control units and gateways are often referred to as <b>endpoints</b>. H.323 uses TCP port number 1720. </p><p>While not all elements are required, at least two terminals are required in order to enable communication between two people. In most H.323 deployments, a gatekeeper is employed in order to, among other things, facilitate address resolution. </p> <div class="mw-heading mw-heading3"><h3 id="H.323_network_elements">H.323 network elements</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=5" title="Edit section: H.323 network elements"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Terminals">Terminals</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=6" title="Edit section: Terminals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Typical_H.323_Stack.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Typical_H.323_Stack.png/500px-Typical_H.323_Stack.png" decoding="async" width="500" height="300" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Typical_H.323_Stack.png/750px-Typical_H.323_Stack.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/93/Typical_H.323_Stack.png/1000px-Typical_H.323_Stack.png 2x" data-file-width="1152" data-file-height="691" /></a><figcaption>Figure 1 - A complete, sophisticated protocol stack</figcaption></figure> <p>Terminals in an H.323 network are the most fundamental elements in any H.323 system, as those are the devices that users would normally encounter. They might exist in the form of a simple IP phone or a powerful high-definition videoconferencing system. </p><p>Inside an H.323 terminal is something referred to as a <a href="/wiki/Protocol_stack" title="Protocol stack">Protocol stack</a>, which implements the functionality defined by the H.323 system. The protocol stack would include an implementation of the basic protocol defined in ITU-T Recommendation H.225.0 and H.245, as well as RTP or other protocols described above. </p><p>The diagram, figure 1, depicts a complete, sophisticated stack that provides support for voice, video, and various forms of data communication. In reality, most H.323 systems do not implement such a wide array of capabilities, but the logical arrangement is useful in understanding the relationships. </p> <div class="mw-heading mw-heading4"><h4 id="Multipoint_control_units">Multipoint control units</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=7" title="Edit section: Multipoint control units"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A <a href="/wiki/Multipoint_control_unit" title="Multipoint control unit">multipoint control unit</a> (MCU) is responsible for managing multipoint conferences and is composed of two logical entities referred to as the <a href="/w/index.php?title=Multipoint_Controller&action=edit&redlink=1" class="new" title="Multipoint Controller (page does not exist)">Multipoint Controller</a> (MC) and the <a href="/w/index.php?title=Multipoint_Processor&action=edit&redlink=1" class="new" title="Multipoint Processor (page does not exist)">Multipoint Processor</a> (MP). In more practical terms, an MCU is a conference bridge not unlike the conference bridges used in the PSTN today. The most significant difference, however, is that H.323 MCUs might be capable of mixing or switching video, in addition to the normal audio mixing done by a traditional conference bridge. Some MCUs also provide multipoint data collaboration capabilities. What this means to the end user is that, by placing a video call into an H.323 MCU, the user might be able to see all of the other participants in the conference, not only hear their voices. </p> <div class="mw-heading mw-heading4"><h4 id="Gateways">Gateways</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=8" title="Edit section: Gateways"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Gateways are devices that enable communication between H.323 networks and other networks, such as PSTN or ISDN networks. If one party in a conversation is utilizing a terminal that is not an H.323 terminal, then the call must pass through a gateway in order to enable both parties to communicate. </p><p>Gateways are widely used today in order to enable the legacy PSTN phones to interconnect with the large, international H.323 networks that are presently deployed by services providers. Gateways are also used within the enterprise in order to enable enterprise IP phones to communicate through the service provider to users on the PSTN. </p><p>Gateways are also used in order to enable videoconferencing devices based on <a href="/wiki/H.320" title="H.320">H.320</a> and <a href="/wiki/H.324" title="H.324">H.324</a> to communicate with H.323 systems. Most of the third generation (3G) mobile networks deployed today utilize the H.324 protocol and are able to communicate with H.323-based terminals in corporate networks through such gateway devices. </p> <div class="mw-heading mw-heading4"><h4 id="Gatekeepers">Gatekeepers</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=9" title="Edit section: Gatekeepers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A Gatekeeper is an optional component in the H.323 network that provides a number of services to terminals, gateways, and MCU devices. Those services include endpoint registration, address resolution, admission control, user authentication, and so forth. Of the various functions performed by the gatekeeper, address resolution is the most important as it enables two endpoints to contact each other without either endpoint having to know the <a href="/wiki/IP_address" title="IP address">IP address</a> of the other endpoint. </p><p>Gatekeepers may be designed to operate in one of two signaling modes, namely "direct routed" and "gatekeeper routed" mode. Direct routed mode is the most efficient and most widely deployed mode. In this mode, endpoints utilize the RAS protocol in order to learn the IP address of the remote endpoint and a call is established directly with the remote device. In the gatekeeper routed mode, call signaling always passes through the gatekeeper. While the latter requires the gatekeeper to have more processing power, it also gives the gatekeeper complete control over the call and the ability to provide supplementary services on behalf of the endpoints. </p><p>H.323 endpoints use the RAS protocol to communicate with a gatekeeper. Likewise, gatekeepers use RAS to communicate with other gatekeepers. </p><p>A collection of endpoints that are registered to a single Gatekeeper in H.323 is referred to as a “zone”. This collection of devices does not necessarily have to have an associated physical topology. Rather, a zone may be entirely logical and is arbitrarily defined by the <a href="/wiki/Network_administrator" title="Network administrator">network administrator</a>. </p><p>Gatekeepers have the ability to neighbor together so that call resolution can happen between zones. Neighboring facilitates the use of dial plans such as the <a href="/wiki/Global_Dialing_Scheme" title="Global Dialing Scheme">Global Dialing Scheme</a>. Dial plans facilitate “inter-zone” dialing so that two endpoints in separate zones can still communicate with each other. </p> <div class="mw-heading mw-heading4"><h4 id="Border_elements_and_peer_elements">Border elements and peer elements</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=10" title="Edit section: Border elements and peer elements"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:H.323_Architecture.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/H.323_Architecture.png/450px-H.323_Architecture.png" decoding="async" width="450" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/H.323_Architecture.png/675px-H.323_Architecture.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/31/H.323_Architecture.png/900px-H.323_Architecture.png 2x" data-file-width="1152" data-file-height="749" /></a><figcaption>Figure 2 - An illustration of an administrative domain with border elements, peer elements, and gatekeepers</figcaption></figure> <p>Border Elements and Peer Elements are optional entities similar to a Gatekeeper, but that do not manage endpoints directly and provide some services that are not described in the RAS protocol. The role of a border or peer element is understood via the definition of an "<a href="/wiki/Administrative_domain" title="Administrative domain">administrative domain</a>". </p><p>An administrative domain is the collection of all zones that are under the control of a single person or organization, such as a service provider. Within a service provider network there may be hundreds or thousands of gateway devices, telephones, video terminals, or other H.323 network elements. The service provider might arrange devices into "zones" that enable the service provider to best manage all of the devices under its control, such as logical arrangement by city. Taken together, all of the zones within the service provider network would appear to another service provider as an "administrative domain". </p><p>The border element is a signaling entity that generally sits at the edge of the administrative domain and communicates with another administrative domain. This communication might include such things as access authorization information; call pricing information; or other important data necessary to enable communication between the two administrative domains. </p><p>Peer elements are entities within the administrative domain that, more or less, help to propagate information learned from the border elements throughout the administrative domain. Such architecture is intended to enable large-scale deployments within carrier networks and to enable services such as <a href="/w/index.php?title=Clearinghouse_(network)&action=edit&redlink=1" class="new" title="Clearinghouse (network) (page does not exist)">clearinghouses</a>. </p><p>The diagram, figure 2, provides an illustration of an administrative domain with border elements, peer elements, and gatekeepers. </p> <div class="mw-heading mw-heading3"><h3 id="H.323_network_signaling">H.323 network signaling</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=11" title="Edit section: H.323 network signaling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>H.323 is defined as a <a href="/wiki/Binary_protocol" class="mw-redirect" title="Binary protocol">binary protocol</a>, which allows for efficient message processing in network elements. The syntax of the protocol is defined in <a href="/wiki/ASN.1" title="ASN.1">ASN.1</a> and uses the <a href="/wiki/Packed_Encoding_Rules" class="mw-redirect" title="Packed Encoding Rules">Packed Encoding Rules</a> (PER) form of message encoding for efficient message encoding on the wire. Below is an overview of the various communication flows in H.323 systems. </p> <div class="mw-heading mw-heading4"><h4 id="H.225.0_call_signaling">H.225.0 call signaling</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=12" title="Edit section: H.225.0 call signaling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Establishment_of_an_H.323_call.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Establishment_of_an_H.323_call.png/300px-Establishment_of_an_H.323_call.png" decoding="async" width="300" height="107" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Establishment_of_an_H.323_call.png/450px-Establishment_of_an_H.323_call.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Establishment_of_an_H.323_call.png/600px-Establishment_of_an_H.323_call.png 2x" data-file-width="1152" data-file-height="411" /></a><figcaption>Figure 3 - Establishment of an H.323 call</figcaption></figure> <p>Once the address of the remote endpoint is resolved, the endpoint will use H.225.0 Call Signaling in order to establish communication with the remote entity. H.225.0 messages are:<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 22em;"> <ul><li>Setup and Setup acknowledge</li> <li>Call Proceeding</li> <li>Connect</li> <li>Alerting</li> <li>Information</li> <li>Release Complete</li> <li>Facility</li> <li>Progress</li> <li>Status and Status Inquiry</li> <li>Notify</li></ul> </div> <p>In the simplest form, an H.323 call may be established as follows (figure 3). </p><p>In this example, the endpoint (EP) on the left initiated communication with the gateway on the right and the gateway connected the call with the called party. In reality, call flows are often more complex than the one shown, but most calls that utilize the Fast Connect procedures defined within H.323 can be established with as few as 2 or 3 messages. Endpoints must notify their gatekeeper (if gatekeepers are used) that they are in a call. </p><p>Once a call has concluded, a device will send a Release Complete message. Endpoints are then required to notify their gatekeeper (if gatekeepers are used) that the call has ended. </p> <div class="mw-heading mw-heading4"><h4 id="RAS_signaling">RAS signaling</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=13" title="Edit section: RAS signaling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:H.323_High-level_call_flow.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/H.323_High-level_call_flow.png/525px-H.323_High-level_call_flow.png" decoding="async" width="525" height="247" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1e/H.323_High-level_call_flow.png/788px-H.323_High-level_call_flow.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1e/H.323_High-level_call_flow.png/1050px-H.323_High-level_call_flow.png 2x" data-file-width="1152" data-file-height="543" /></a><figcaption>Figure 4 - A high-level communication exchange between two endpoints (EP) and two gatekeepers (GK)</figcaption></figure> <p>Endpoints use the RAS protocol in order to communicate with a gatekeeper. Likewise, gatekeepers use RAS to communicate with peer gatekeepers. RAS is a fairly simple protocol composed of just a few messages. Namely: </p> <ul><li>Gatekeeper request, reject and confirm messages (GRx)</li> <li>Registration request, reject and confirm messages (RRx)</li> <li>Unregister request, reject and confirm messages (URx)</li> <li>Admission request, reject and confirm messages (ARx)</li> <li>Bandwidth request, reject and confirm message (BRx)</li> <li>Disengage request, reject and confirm (DRx)</li> <li>Location request, reject and confirm messages (LRx)</li> <li>Info request, ack, nack and response (IRx)</li> <li>Nonstandard message</li> <li>Unknown message response</li> <li>Request in progress (RIP)</li> <li>Resource availability indication and confirm (RAx)</li> <li>Service control indication and response (SCx)</li></ul> <p>When an endpoint is powered on, it will generally send a gatekeeper request (GRQ) message to "discover" gatekeepers that are willing to provide service. Gatekeepers will then respond with a gatekeeper confirm (GCF) and the endpoint will then select a gatekeeper to work with. Alternatively, it is possible that a gatekeeper has been predefined in the system’s administrative setup so there is no need for the endpoint to discover one. </p><p>Once the endpoint determines the gatekeeper to work with, it will try to register with the gatekeeper by sending a registration request (RRQ), to which the gatekeeper responds with a registration confirm (RCF). At this point, the endpoint is known to the network and can make and place calls. </p><p>When an endpoint wishes to place a call, it will send an admission request (ARQ) to the gatekeeper. The gatekeeper will then resolve the address (either locally, by consulting another gatekeeper, or by querying some other network service) and return the address of the remote endpoint in the admission confirm message (ACF). The endpoint can then place the call. </p><p>Upon receiving a call, a remote endpoint will also send an ARQ and receive an ACF in order to get permission to accept the incoming call. This is necessary, for example, to authenticate the calling device or to ensure that there is available <a href="/wiki/Bandwidth_(computing)" title="Bandwidth (computing)">bandwidth</a> for the call. </p><p>Figure 4 depicts a high-level communication exchange between two endpoints (EP) and two gatekeepers (GK). </p> <div class="mw-heading mw-heading4"><h4 id="H.245_call_control">H.245 call control</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=14" title="Edit section: H.245 call control"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Once a call has initiated (but not necessarily fully connected) endpoints may initiate H.245 call control signaling in order to provide more extensive control over the conference. H.245 is a rather voluminous specification with many procedures that fully enable multipoint communication, though in practice most implementations only implement the minimum necessary in order to enable <a href="/wiki/Point-to-point_telecommunications" class="mw-redirect" title="Point-to-point telecommunications">point-to-point</a> voice and video communication. </p><p>H.245 provides capabilities such as capability negotiation, <a href="/wiki/Master/slave_(technology)" class="mw-redirect" title="Master/slave (technology)">master/slave</a> determination, opening and closing of "logical channels" (i.e., audio and video flows), flow control, and conference control. It has support for both <a href="/wiki/Unicast" title="Unicast">unicast</a> and <a href="/wiki/Multicast" title="Multicast">multicast</a> communication, allowing the size of a conference to theoretically grow without bound. </p> <div class="mw-heading mw-heading5"><h5 id="Capability_negotiation">Capability negotiation</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=15" title="Edit section: Capability negotiation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Of the functionality provided by H.245, capability negotiation is arguably the most important, as it enables devices to communicate without having prior knowledge of the capabilities of the remote entity. H.245 enables rich multimedia capabilities, including audio, video, text, and data communication. For transmission of audio, video, or text, H.323 devices utilize both ITU-defined codecs and codecs defined outside the ITU. Codecs that are widely implemented by H.323 equipment include: </p> <ul><li>Video codecs: <a href="/wiki/H.261" title="H.261">H.261</a>, <a href="/wiki/H.263" title="H.263">H.263</a>, <a href="/wiki/H.264" class="mw-redirect" title="H.264">H.264</a></li> <li>Audio codecs: <a href="/wiki/G.711" title="G.711">G.711</a>, <a href="/wiki/G.729" title="G.729">G.729</a>, <a href="/wiki/G.729a" class="mw-redirect" title="G.729a">G.729a</a>, <a href="/wiki/G.723.1" title="G.723.1">G.723.1</a>, <a href="/wiki/G.726" title="G.726">G.726</a></li> <li>Text codecs: <a href="/wiki/Text_over_IP" title="Text over IP">T.140</a></li></ul> <p>H.245 also enables real-time data conferencing capability through protocols like <a href="/wiki/T.120" title="T.120">T.120</a>. T.120-based applications generally operate in parallel with the H.323 system, but are integrated to provide the user with a seamless multimedia experience. T.120 provides such capabilities as application sharing <a href="/wiki/T.128" class="mw-redirect" title="T.128">T.128</a>, electronic whiteboard <a href="/wiki/T.126" class="mw-redirect" title="T.126">T.126</a>, file transfer <a href="/wiki/T.127" class="mw-redirect" title="T.127">T.127</a>, and text chat <a href="/w/index.php?title=T.134&action=edit&redlink=1" class="new" title="T.134 (page does not exist)">T.134</a> within the context of the conference. </p><p>When an H.323 device initiates communication with a remote H.323 device and when H.245 communication is established between the two entities, the Terminal Capability Set (TCS) message is the first message transmitted to the other side. </p> <div class="mw-heading mw-heading5"><h5 id="Master/slave_determination"><span id="Master.2Fslave_determination"></span>Master/slave determination</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=16" title="Edit section: Master/slave determination"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>After sending a TCS message, H.323 entities (through H.245 exchanges) will attempt to determine which device is the "master" and which is the "slave." This process, referred to as Master/Slave Determination (MSD), is important, as the master in a call settles all "disputes" between the two devices. For example, if both endpoints attempt to open incompatible media flows, it is the master who takes the action to reject the incompatible flow. </p> <div class="mw-heading mw-heading5"><h5 id="Logical_channel_signaling">Logical channel signaling</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=17" title="Edit section: Logical channel signaling"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Once capabilities are exchanged and master/slave determination steps have completed, devices may then open "logical channels" or media flows. This is done by simply sending an Open Logical Channel (OLC) message and receiving an acknowledgement message. Upon receipt of the acknowledgement message, an endpoint may then transmit audio or video to the remote endpoint. </p> <div class="mw-heading mw-heading5"><h5 id="Fast_connect">Fast connect</h5><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=18" title="Edit section: Fast connect"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:A_typical_H.245_exchange.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3a/A_typical_H.245_exchange.png/300px-A_typical_H.245_exchange.png" decoding="async" width="300" height="180" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3a/A_typical_H.245_exchange.png/450px-A_typical_H.245_exchange.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3a/A_typical_H.245_exchange.png/600px-A_typical_H.245_exchange.png 2x" data-file-width="1152" data-file-height="693" /></a><figcaption>Figure 5 - A typical H.245 exchange</figcaption></figure> <p>A typical H.245 exchange looks similar to figure 5: </p><p>After this exchange of messages, the two endpoints (EP) in this figure would be transmitting audio in each direction. The number of message exchanges is numerous, each has an important purpose, but nonetheless takes time. </p><p>For this reason, H.323 version 2 (published in 1998) introduced a concept called Fast Connect, which enables a device to establish <a href="/wiki/Duplex_(telecommunications)" title="Duplex (telecommunications)">bi-directional</a> media flows as part of the H.225.0 call establishment procedures. With Fast Connect, it is possible to establish a call with bi-directional media flowing with no more than two messages, like in figure 3. </p><p>Fast Connect is widely supported in the industry. Even so, most devices still implement the complete H.245 exchange as shown above and perform that message exchange in parallel to other activities, so there is no noticeable delay to the calling or called party. </p> <div class="mw-heading mw-heading2"><h2 id="Use_cases">Use cases</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=19" title="Edit section: Use cases"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="H.323_and_voice_over_IP_services">H.323 and voice over IP services</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=20" title="Edit section: H.323 and voice over IP services"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Voice over Internet Protocol (VoIP) describes the transmission of voice using the Internet or other packet switched networks. ITU-T Recommendation H.323 is one of the standards used in VoIP. VoIP requires a connection to the Internet or another packet switched network, a subscription to a VoIP service provider and a client (an <a href="/wiki/Analog_telephony_adapter" class="mw-redirect" title="Analog telephony adapter">analogue telephone adapter</a> (ATA), VoIP Phone or "<a href="/wiki/Soft_phone" class="mw-redirect" title="Soft phone">soft phone</a>"). The service provider offers the connection to other VoIP services or to the PSTN. Most service providers charge a monthly fee, then additional costs when calls are made.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2009)">citation needed</span></a></i>]</sup> Using VoIP between two enterprise locations would not necessarily require a VoIP service provider, for example. H.323 has been widely deployed by companies who wish to interconnect remote locations over IP using a number of various wired and wireless technologies. </p> <div class="mw-heading mw-heading3"><h3 id="H.323_and_videoconference_services">H.323 and videoconference services</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=21" title="Edit section: H.323 and videoconference services"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A videoconference, or videoteleconference (VTC), is a set of <a href="/wiki/Telecommunication" class="mw-redirect" title="Telecommunication">telecommunication</a> <a href="/wiki/Technology" title="Technology">technologies</a> allowing two or more locations to interact via two-way video and audio transmissions simultaneously. There are basically two types of videoconferencing; dedicated VTC systems have all required components packaged into a single piece of equipment while desktop VTC systems are add-ons to normal <a href="/wiki/Personal_computer" title="Personal computer">PC's</a>, transforming them into VTC devices. Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). There are MCU bridges for IP and ISDN-based videoconferencing. Due to the price point and proliferation of the Internet, and broadband in particular, there has been a strong spurt of growth and use of H.323-based IP videoconferencing. H.323 is accessible to anyone with a high speed Internet connection, such as <a href="/wiki/DSL" class="mw-redirect" title="DSL">DSL</a>. Videoconferencing is utilized in various situations, for example; <a href="/wiki/Remote_learning" class="mw-redirect" title="Remote learning">distance education</a>, <a href="/wiki/Telemedicine" class="mw-redirect" title="Telemedicine">telemedicine</a>, <a href="/wiki/Video_Relay_Service" class="mw-redirect" title="Video Relay Service">Video Relay Service</a>, and business.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2009)">citation needed</span></a></i>]</sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers"><span title="The date of the event predicted near this tag has passed. (June 2021)">needs update</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Alternatives">Alternatives</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=22" title="Edit section: Alternatives"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Inter-Asterisk_eXchange" title="Inter-Asterisk eXchange">IAX2</a> - Inter-Asterisk eXchange, a binary protocol, designed to reduce overhead especially in regard to voice streams. Defined in RFC 5456.</li> <li>The IETF produced a standard called the <a href="/wiki/Session_Initiation_Protocol" title="Session Initiation Protocol">Session Initiation Protocol</a> (SIP) that also enables voice and video communication over IP.</li> <li>There are also other ITU-T recommendations used for videoconferencing and videophone services – <a href="/wiki/H.320" title="H.320">H.320</a> (using ISDN) and <a href="/wiki/H.324" title="H.324">H.324</a> (using regular analog phone lines and 3G mobile phones).</li> <li><a href="/wiki/Jingle_(protocol)" title="Jingle (protocol)">Jingle</a> (Jabber/<a href="/wiki/XMPP" title="XMPP">XMPP</a> extension) also enables video and voice over IP.</li> <li>Some providers (such as Skype) also use their own closed, <a href="/wiki/Comparison_of_VoIP_software" title="Comparison of VoIP software">proprietary formats</a>.</li> <li><a href="/wiki/Access_Grid" title="Access Grid">Access Grid</a> provides broadly similar functionality, with more emphasis on open-source and utilizing multicast.</li> <li>EVO also provides relatively open functionality via Java, and includes H.323 support.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=23" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1184024115"><div class="div-col" style="column-width: 25em;"> <ul><li><a href="/wiki/Global_Dialing_Scheme" title="Global Dialing Scheme">Global Dialing Scheme (GDS)</a></li> <li><a href="/wiki/H.323_Gatekeeper" title="H.323 Gatekeeper">H.323 Gatekeeper</a></li> <li><a href="/wiki/Next-generation_network" title="Next-generation network">Next-generation network</a></li> <li><a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">Internet Engineering Task Force (IETF)</a></li> <li><a href="/wiki/ITU-T" title="ITU-T">International Telecommunication Union (ITU) Telecommunications Standardization Sector (ITU-T)</a></li> <li><a href="/wiki/Multipoint_Control_Unit" class="mw-redirect" title="Multipoint Control Unit">Multipoint Control Units (MCU)</a></li> <li><a href="/wiki/Videoconferencing" class="mw-redirect" title="Videoconferencing">Videoconferencing</a></li> <li><a href="/wiki/Voice_over_IP" title="Voice over IP">Voice over IP (VoIP)</a></li> <li><a href="/wiki/Session_Initiation_Protocol" title="Session Initiation Protocol">Session Initiation Protocol (SIP)</a></li> <li><a href="/wiki/Lifesize_communications" class="mw-redirect" title="Lifesize communications">LifeSize Communications</a></li> <li><a href="/wiki/Polycom" class="mw-redirect" title="Polycom">Polycom</a></li> <li><a href="/wiki/RTP_audio_video_profile" class="mw-redirect" title="RTP audio video profile">RTP audio video profile</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=24" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.itu.int/rec/T-REC-H.323">"H.323: Packet-based multimedia communications systems"</a>. <i>www.itu.int</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210429130239/https://www.itu.int/rec/T-REC-H.323">Archived</a> from the original on 2021-04-29<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-04-29</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.itu.int&rft.atitle=H.323%3A+Packet-based+multimedia+communications+systems&rft_id=https%3A%2F%2Fwww.itu.int%2Frec%2FT-REC-H.323&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.323" class="Z3988"></span></span> </li> <li id="cite_note-Davidson-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Davidson_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDavidsonJames_PetersJim_PetersBrian_Gracely2000" class="citation book cs1">Davidson, Jonathan; James Peters; Jim Peters; Brian Gracely (2000). "H.323". <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9781578701681"><i>Voice over IP fundamentals</i></a></span>. Cisco Press. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9781578701681/page/229">229</a>–230. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-57870-168-1" title="Special:BookSources/978-1-57870-168-1"><bdi>978-1-57870-168-1</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=H.323&rft.btitle=Voice+over+IP+fundamentals&rft.pages=229-230&rft.pub=Cisco+Press&rft.date=2000&rft.isbn=978-1-57870-168-1&rft.aulast=Davidson&rft.aufirst=Jonathan&rft.au=James+Peters&rft.au=Jim+Peters&rft.au=Brian+Gracely&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fisbn_9781578701681&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.323" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160515184110/http://www.h323forum.org/products_services/">"H.323 Products & Services"</a>. Archived from the original on 15 May 2016.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=H.323+Products+%26+Services&rft_id=http%3A%2F%2Fwww.h323forum.org%2Fproducts_services%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.323" class="Z3988"></span><span class="cs1-maint citation-comment"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: unfit URL (<a href="/wiki/Category:CS1_maint:_unfit_URL" title="Category:CS1 maint: unfit URL">link</a>)</span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.323-199611-S/en/">ITU-T Recommendation H.323 (11/1996)</a>, first version of H.323.</span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.323/en/">ITU-T Recommendation H.323</a>, in force, superseded and withdrawn component.</span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.323-199802-S/en/">ITU-T Recommendation H.323 (02/1998)</a>, <i>Packet-based multimedia communications systems</i>.</span> </li> <li id="cite_note-h323-12-2009-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-h323-12-2009_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-h323-12-2009_7-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.itu.int/rec/T-REC-H.323">ITU-T Recommendation H.323 (12/2009)</a>, <i>Packet-based multimedia communications systems</i>.</span> </li> <li id="cite_note-itulist-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-itulist_8-0">^</a></b></span> <span class="reference-text">See <a class="mw-selflink-fragment" href="#ITU-T_Recommendations_of_the_H.323_System">ITU-T Recommendations of the H.323 System</a> for a detailed list.</span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.itu.int/rec/T-REC-H.225.0/en">"H.225.0 : Call signalling protocols and media stream packetization for packet-based multimedia communication systems"</a>. <i>www.itu.int</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.itu.int&rft.atitle=H.225.0+%3A+Call+signalling+protocols+and+media+stream+packetization+for+packet-based+multimedia+communication+systems&rft_id=https%3A%2F%2Fwww.itu.int%2Frec%2FT-REC-H.225.0%2Fen&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.323" class="Z3988"></span></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100218130500/http://evo.caltech.edu/evoGate/">"EVO The Collaboration Network"</a>. Archived from <a rel="nofollow" class="external text" href="http://evo.caltech.edu/evoGate">the original</a> on 2010-02-18<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-03-08</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=EVO+The+Collaboration+Network&rft_id=http%3A%2F%2Fevo.caltech.edu%2FevoGate&rfr_id=info%3Asid%2Fen.wikipedia.org%3AH.323" class="Z3988"></span><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability"><span title="The citation is not specific enough to facilitate source verification (March 2011)">not specific enough to verify</span></a></i>]</sup></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=H.323&action=edit&section=25" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://www.packetizer.com/ipmc/h323/">H.323 Information site</a></li> <li><a rel="nofollow" class="external text" href="https://www.h323plus.org/">H.323 Plus open source H.323 project</a></li> <li><a rel="nofollow" class="external text" href="https://www.gnugk.org/">GNU (OpenSource) Gatekeeper</a></li></ul> <p><br /> </p> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Multimedia_compression_and_container_formats" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Compression_formats" title="Template:Compression formats"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Compression_formats" title="Template talk:Compression formats"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Compression_formats" title="Special:EditPage/Template:Compression formats"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Multimedia_compression_and_container_formats" style="font-size:114%;margin:0 4em"><a href="/wiki/Multimedia" title="Multimedia">Multimedia</a> <a href="/wiki/Data_compression" title="Data compression">compression</a> and <a href="/wiki/Container_format_(computing)" class="mw-redirect" title="Container format (computing)">container</a> formats</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Video_coding_format" title="Video coding format">Video<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>, <br /><a href="/wiki/Moving_Picture_Experts_Group" title="Moving Picture Experts Group">MPEG</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/DV_(video_format)" title="DV (video format)">DV</a></li> <li><a href="/wiki/Motion_JPEG" title="Motion JPEG">MJPEG</a></li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">Motion JPEG 2000</a></li> <li><a href="/wiki/MPEG-1" title="MPEG-1">MPEG-1</a></li> <li><a href="/wiki/MPEG-2" title="MPEG-2">MPEG-2</a> <ul><li><a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">Part 2</a></li></ul></li> <li><a href="/wiki/MPEG-4" title="MPEG-4">MPEG-4</a> <ul><li><a href="/wiki/MPEG-4_Part_2" title="MPEG-4 Part 2">Part 2 / ASP</a></li> <li><a href="/wiki/H.264/MPEG-4_AVC" class="mw-redirect" title="H.264/MPEG-4 AVC">Part 10 / AVC</a></li> <li><a href="/wiki/MPEG-4_IVC" class="mw-redirect" title="MPEG-4 IVC">Part 33 / IVC</a></li></ul></li> <li><a href="/wiki/MPEG-H" title="MPEG-H">MPEG-H</a> <ul><li><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">Part 2 / HEVC</a></li></ul></li> <li><a href="/w/index.php?title=MPEG-I&action=edit&redlink=1" class="new" title="MPEG-I (page does not exist)">MPEG-I</a> <ul><li><a href="/wiki/Versatile_Video_Coding" title="Versatile Video Coding">Part 3 / VVC</a></li></ul></li> <li><a href="/wiki/MPEG-5" class="mw-redirect" title="MPEG-5">MPEG-5</a> <ul><li><a href="/wiki/Essential_Video_Coding" title="Essential Video Coding">Part 1 / EVC</a></li> <li><a href="/wiki/LCEVC" title="LCEVC">Part 2 / LCEVC</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a>, <a href="/wiki/Video_Coding_Experts_Group" title="Video Coding Experts Group">VCEG</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/H.120" title="H.120">H.120</a></li> <li><a href="/wiki/H.261" title="H.261">H.261</a></li> <li><a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">H.262</a></li> <li><a href="/wiki/H.263" title="H.263">H.263</a></li> <li><a href="/wiki/Advanced_Video_Coding" title="Advanced Video Coding">H.264 / AVC</a></li> <li><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">H.265 / HEVC</a></li> <li><a href="/wiki/Versatile_Video_Coding" title="Versatile Video Coding">H.266 / VVC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">SMPTE</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/VC-1" title="VC-1">VC-1</a></li> <li><a href="/wiki/Dirac_(video_compression_format)" title="Dirac (video compression format)">VC-2</a></li> <li><a href="/wiki/Avid_DNxHD" title="Avid DNxHD">VC-3</a></li> <li><a href="/wiki/CineForm" title="CineForm">VC-5</a></li> <li><a href="/wiki/VC-6" title="VC-6">VC-6</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/On2_Technologies" title="On2 Technologies">TrueMotion</a> and AOMedia</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/On2_Technologies#TrueMotion_S" title="On2 Technologies">TrueMotion S</a></li> <li><a href="/wiki/VP3" title="VP3">VP3</a></li> <li><a href="/wiki/VP6" title="VP6">VP6</a></li> <li><a href="/wiki/VP7" class="mw-redirect" title="VP7">VP7</a></li> <li><a href="/wiki/VP8" title="VP8">VP8</a></li> <li><a href="/wiki/VP9" title="VP9">VP9</a></li> <li><a href="/wiki/AV1" title="AV1">AV1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Chinese Standard</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Audio_Video_Standard#First_generation" title="Audio Video Standard">AVS1 P2/AVS+</a>(GB/T 20090.2/16)</li> <li><a href="/wiki/Audio_Video_Standard#Second_generation" title="Audio Video Standard">AVS2 P2</a>(GB/T 33475.2,GY/T 299.1) <ul><li>HDR Vivid(GY/T 358)</li></ul></li> <li>AVS3 P2(GY/T 368)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Apple_Video" title="Apple Video">Apple Video</a></li> <li><a href="/wiki/Audio_Video_Standard" title="Audio Video Standard">AVS</a></li> <li><a href="/wiki/Bink_Video" title="Bink Video">Bink</a></li> <li><a href="/wiki/Cinepak" title="Cinepak">Cinepak</a></li> <li><a href="/wiki/Daala" title="Daala">Daala</a></li> <li><a href="/wiki/Digital_Video_Interactive" title="Digital Video Interactive">DVI</a></li> <li><a href="/wiki/FFV1" title="FFV1">FFV1</a></li> <li><a href="/wiki/Huffyuv" title="Huffyuv">Huffyuv</a></li> <li><a href="/wiki/Indeo" title="Indeo">Indeo</a></li> <li><a href="/wiki/Lagarith" title="Lagarith">Lagarith</a></li> <li><a href="/wiki/Microsoft_Video_1" title="Microsoft Video 1">Microsoft Video 1</a></li> <li><a href="/wiki/MSU_Lossless_Video_Codec" title="MSU Lossless Video Codec">MSU Lossless</a></li> <li><a href="/wiki/OMS_Video" title="OMS Video">OMS Video</a></li> <li><a href="/wiki/Pixlet" title="Pixlet">Pixlet</a></li> <li><a href="/wiki/Apple_ProRes" title="Apple ProRes">ProRes</a> <ul><li><a href="/wiki/ProRes_422" class="mw-redirect" title="ProRes 422">422</a></li> <li><a href="/wiki/ProRes_4444" class="mw-redirect" title="ProRes 4444">4444</a></li></ul></li> <li>QuickTime <ul><li><a href="/wiki/QuickTime_Animation" title="QuickTime Animation">Animation</a></li> <li><a href="/wiki/QuickTime_Graphics" title="QuickTime Graphics">Graphics</a></li></ul></li> <li><a href="/wiki/RealVideo" title="RealVideo">RealVideo</a></li> <li><a href="/wiki/RTVideo" title="RTVideo">RTVideo</a></li> <li><a href="/wiki/SheerVideo" title="SheerVideo">SheerVideo</a></li> <li><a href="/wiki/Smacker_video" title="Smacker video">Smacker</a></li> <li><a href="/wiki/Sorenson_Media" title="Sorenson Media">Sorenson Video/Spark</a></li> <li><a href="/wiki/Theora" title="Theora">Theora</a></li> <li><a href="/wiki/Thor_(video_codec)" title="Thor (video codec)">Thor</a></li> <li><a href="/wiki/Ut_Video_Codec_Suite" title="Ut Video Codec Suite">Ut</a></li> <li><a href="/wiki/Windows_Media_Video" title="Windows Media Video">WMV</a></li> <li><a href="/wiki/RatDVD" title="RatDVD">XEB</a></li> <li><a href="/wiki/YULS" title="YULS">YULS</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Audio_coding_format" title="Audio coding format">Audio<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>,<br /> <a href="/wiki/Moving_Picture_Experts_Group" title="Moving Picture Experts Group">MPEG</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/MPEG-1_Audio_Layer_II" title="MPEG-1 Audio Layer II">MPEG-1 Layer II</a> <ul><li><a href="/wiki/MPEG_Multichannel" title="MPEG Multichannel">Multichannel</a></li></ul></li> <li><a href="/wiki/MPEG-1_Audio_Layer_I" title="MPEG-1 Audio Layer I">MPEG-1 Layer I</a></li> <li><a href="/wiki/MP3" title="MP3">MPEG-1 Layer III (MP3)</a></li> <li><a href="/wiki/Advanced_Audio_Coding" title="Advanced Audio Coding">AAC</a> <ul><li><a href="/wiki/High-Efficiency_Advanced_Audio_Coding" title="High-Efficiency Advanced Audio Coding">HE-AAC</a></li> <li><a href="/wiki/AAC-LD" title="AAC-LD">AAC-LD</a></li></ul></li> <li><a href="/wiki/MPEG_Surround" title="MPEG Surround">MPEG Surround</a></li> <li><a href="/wiki/Audio_Lossless_Coding" title="Audio Lossless Coding">MPEG-4 ALS</a></li> <li><a href="/wiki/MPEG-4_SLS" title="MPEG-4 SLS">MPEG-4 SLS</a></li> <li><a href="/wiki/Super_Audio_CD#DST" title="Super Audio CD">MPEG-4 DST</a></li> <li><a href="/wiki/Harmonic_Vector_Excitation_Coding" title="Harmonic Vector Excitation Coding">MPEG-4 HVXC</a></li> <li><a href="/wiki/Code-excited_linear_prediction" title="Code-excited linear prediction">MPEG-4 CELP</a></li> <li><a href="/wiki/Unified_Speech_and_Audio_Coding" title="Unified Speech and Audio Coding">MPEG-D USAC</a></li> <li><a href="/wiki/MPEG-H_3D_Audio" title="MPEG-H 3D Audio">MPEG-H 3D Audio</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/G.711" title="G.711">G.711</a> <ul><li><a href="/wiki/A-law_algorithm" title="A-law algorithm">A-law</a></li> <li><a href="/wiki/%CE%9C-law_algorithm" title="Μ-law algorithm">µ-law</a></li></ul></li> <li><a href="/wiki/G.718" title="G.718">G.718</a></li> <li><a href="/wiki/G.719" title="G.719">G.719</a></li> <li><a href="/wiki/G.722" title="G.722">G.722</a></li> <li><a href="/wiki/G.722.1" title="G.722.1">G.722.1</a></li> <li><a href="/wiki/Adaptive_Multi-Rate_Wideband" title="Adaptive Multi-Rate Wideband">G.722.2</a></li> <li><a href="/wiki/G.723" title="G.723">G.723</a></li> <li><a href="/wiki/G.723.1" title="G.723.1">G.723.1</a></li> <li><a href="/wiki/G.726" title="G.726">G.726</a></li> <li><a href="/wiki/G.728" title="G.728">G.728</a></li> <li><a href="/wiki/G.729" title="G.729">G.729</a></li> <li><a href="/wiki/G.729.1" title="G.729.1">G.729.1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Opus_(audio_format)" title="Opus (audio format)">Opus</a></li> <li><a href="/wiki/Internet_Low_Bitrate_Codec" title="Internet Low Bitrate Codec">iLBC</a></li> <li><a href="/wiki/Speex" title="Speex">Speex</a></li> <li><a href="/wiki/Vorbis" title="Vorbis">Vorbis</a></li> <li><a href="/wiki/FLAC" title="FLAC">FLAC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/3GPP" title="3GPP">3GPP</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adaptive_Multi-Rate_audio_codec" title="Adaptive Multi-Rate audio codec">AMR</a></li> <li><a href="/wiki/Adaptive_Multi-Rate_Wideband" title="Adaptive Multi-Rate Wideband">AMR-WB</a></li> <li><a href="/wiki/Extended_Adaptive_Multi-Rate_%E2%80%93_Wideband" title="Extended Adaptive Multi-Rate – Wideband">AMR-WB+</a></li> <li><a href="/wiki/Enhanced_Variable_Rate_Codec" title="Enhanced Variable Rate Codec">EVRC</a></li> <li><a href="/wiki/Enhanced_Variable_Rate_Codec_B" title="Enhanced Variable Rate Codec B">EVRC-B</a></li> <li><a href="/wiki/Enhanced_Voice_Services" title="Enhanced Voice Services">EVS</a></li> <li><a href="/wiki/Half_Rate" title="Half Rate">GSM-HR</a></li> <li><a href="/wiki/Full_Rate" title="Full Rate">GSM-FR</a></li> <li><a href="/wiki/Enhanced_full_rate" title="Enhanced full rate">GSM-EFR</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ETSI" class="mw-redirect" title="ETSI">ETSI</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Dolby_Digital" title="Dolby Digital">AC-3</a></li> <li><a href="/wiki/Dolby_AC-4" title="Dolby AC-4">AC-4</a></li> <li><a href="/wiki/DTS_(sound_system)" class="mw-redirect" title="DTS (sound system)">DTS</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Bluetooth_Special_Interest_Group" title="Bluetooth Special Interest Group">Bluetooth SIG</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/SBC_(codec)" title="SBC (codec)">SBC</a></li> <li><a href="/wiki/LC3_(codec)" title="LC3 (codec)">LC3</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Chinese Standard</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Audio_Video_Standard#First_generation" title="Audio Video Standard">AVS1 P10</a>(GB/T 20090.10)</li> <li><a href="/wiki/Audio_Video_Standard#Second_generation" title="Audio Video Standard">AVS2 P3</a>(GB/T 33475.3) <ul><li><a href="/w/index.php?title=Audio_Vivid&action=edit&redlink=1" class="new" title="Audio Vivid (page does not exist)">Audio Vivid</a>(GY/T 363)</li></ul></li> <li><a href="/wiki/Dynamic_Resolution_Adaptation" title="Dynamic Resolution Adaptation">DRA</a>(GB/T 22726)</li> <li><a href="/wiki/L2HC" title="L2HC">L2HC</a></li> <li>ExAC(SJ/T 11299.4)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Algebraic_code-excited_linear_prediction" title="Algebraic code-excited linear prediction">ACELP</a></li> <li><a href="/wiki/Apple_Lossless_Audio_Codec" title="Apple Lossless Audio Codec">ALAC</a></li> <li><a href="/wiki/Asao_(codec)" title="Asao (codec)">Asao</a></li> <li><a href="/wiki/Adaptive_Transform_Acoustic_Coding" class="mw-redirect" title="Adaptive Transform Acoustic Coding">ATRAC</a></li> <li><a href="/wiki/CELT" title="CELT">CELT</a></li> <li><a href="/wiki/Codec_2" title="Codec 2">Codec 2</a></li> <li><a href="/wiki/Internet_Speech_Audio_Codec" title="Internet Speech Audio Codec">iSAC</a></li> <li><a href="/wiki/Lyra_(codec)" title="Lyra (codec)">Lyra</a></li> <li><a href="/wiki/Mixed-excitation_linear_prediction" title="Mixed-excitation linear prediction">MELP</a></li> <li><a href="/wiki/Monkey%27s_Audio" title="Monkey's Audio">Monkey's Audio</a></li> <li><a href="/wiki/MT9" title="MT9">MT9</a></li> <li><a href="/wiki/Musepack" title="Musepack">Musepack</a></li> <li><a href="/wiki/OptimFROG" title="OptimFROG">OptimFROG</a></li> <li><a href="/wiki/Original_Sound_Quality" title="Original Sound Quality">OSQ</a></li> <li><a href="/wiki/Qualcomm_code-excited_linear_prediction" title="Qualcomm code-excited linear prediction">QCELP</a></li> <li><a href="/wiki/Relaxed_code-excited_linear_prediction" title="Relaxed code-excited linear prediction">RCELP</a></li> <li><a href="/wiki/RealAudio" title="RealAudio">RealAudio</a></li> <li><a href="/wiki/RTAudio" title="RTAudio">RTAudio</a></li> <li><a href="/wiki/Avid_Audio#Sound_Designer_file_formats" title="Avid Audio">SD2</a></li> <li><a href="/wiki/Shorten_file_format" class="mw-redirect" title="Shorten file format">SHN</a></li> <li><a href="/wiki/SILK" title="SILK">SILK</a></li> <li><a href="/wiki/Siren_(codec)" title="Siren (codec)">Siren</a></li> <li><a href="/wiki/Selectable_Mode_Vocoder" title="Selectable Mode Vocoder">SMV</a></li> <li><a href="/wiki/SVOPC" title="SVOPC">SVOPC</a></li> <li>TTA <ul><li>True Audio</li></ul></li> <li><a href="/wiki/TwinVQ" title="TwinVQ">TwinVQ</a></li> <li><a href="/wiki/Variable-Rate_Multimode_Wideband" title="Variable-Rate Multimode Wideband">VMR-WB</a></li> <li><a href="/wiki/Vector_sum_excited_linear_prediction" title="Vector sum excited linear prediction">VSELP</a></li> <li><a href="/wiki/WavPack" title="WavPack">WavPack</a></li> <li><a href="/wiki/Windows_Media_Audio" title="Windows Media Audio">WMA</a></li> <li><a href="/wiki/Master_Quality_Authenticated" title="Master Quality Authenticated">MQA</a></li> <li><a href="/wiki/AptX" title="AptX">aptX</a></li> <li><a href="/wiki/AptX#aptX_HD" title="AptX">aptX HD</a></li> <li><a href="/wiki/AptX#aptX_Low_Latency" title="AptX">aptX Low Latency</a></li> <li><a href="/wiki/AptX#aptX_Adaptive" title="AptX">aptX Adaptive</a></li> <li><a href="/wiki/LDAC_(codec)" title="LDAC (codec)">LDAC</a></li> <li><a href="/wiki/LHDC_(codec)" title="LHDC (codec)">LHDC</a></li> <li><a href="/wiki/LHDC_(codec)#LLAC" title="LHDC (codec)">LLAC</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Image_compression" title="Image compression">Image<br />compression</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a>, <a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</a>, <br /><a href="/wiki/World_Wide_Web_Consortium" title="World Wide Web Consortium">W3C</a>, <a href="/wiki/ITU-T" title="ITU-T">ITU-T</a>, <a href="/wiki/Joint_Photographic_Experts_Group" title="Joint Photographic Experts Group">JPEG</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Group_4_compression" title="Group 4 compression">CCITT Group 4</a></li> <li><a href="/wiki/GIF" title="GIF">GIF</a></li> <li><a href="/wiki/High_Efficiency_Image_File_Format#HEIC:_HEVC_in_HEIF" title="High Efficiency Image File Format">HEIC / HEIF</a></li> <li><a href="/wiki/High_Efficiency_Video_Coding#Main_Still_Picture" title="High Efficiency Video Coding">HEVC</a></li> <li><a href="/wiki/JBIG" title="JBIG">JBIG</a></li> <li><a href="/wiki/JBIG2" title="JBIG2">JBIG2</a></li> <li><a href="/wiki/JPEG" title="JPEG">JPEG</a></li> <li><a href="/wiki/JPEG_2000" title="JPEG 2000">JPEG 2000</a></li> <li><a href="/wiki/JPEG-LS" class="mw-redirect" title="JPEG-LS">JPEG-LS</a></li> <li><a href="/wiki/JPEG_XL" title="JPEG XL">JPEG XL</a></li> <li><a href="/wiki/JPEG_XR" title="JPEG XR">JPEG XR</a></li> <li><a href="/wiki/JPEG_XS" title="JPEG XS">JPEG XS</a></li> <li><a href="/wiki/JPEG_XT" title="JPEG XT">JPEG XT</a></li> <li><a href="/wiki/Portable_Network_Graphics" class="mw-redirect" title="Portable Network Graphics">PNG</a></li> <li><a href="/wiki/TIFF" title="TIFF">TIFF</a></li> <li><a href="/wiki/TIFF/EP" title="TIFF/EP">TIFF/EP</a></li> <li><a href="/wiki/TIFF/IT" class="mw-redirect" title="TIFF/IT">TIFF/IT</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/APNG" title="APNG">APNG</a></li> <li><a href="/wiki/AV1" title="AV1">AV1</a></li> <li><a href="/wiki/AVIF" title="AVIF">AVIF</a></li> <li><a href="/wiki/Better_Portable_Graphics" title="Better Portable Graphics">BPG</a></li> <li><a href="/wiki/DjVu" title="DjVu">DjVu</a></li> <li><a href="/wiki/OpenEXR" title="OpenEXR">EXR</a></li> <li><a href="/wiki/Free_Lossless_Image_Format" title="Free Lossless Image Format">FLIF</a></li> <li><a href="/wiki/ICER_(file_format)" title="ICER (file format)">ICER</a></li> <li><a href="/wiki/Multiple-image_Network_Graphics" title="Multiple-image Network Graphics">MNG</a></li> <li><a href="/wiki/Progressive_Graphics_File" title="Progressive Graphics File">PGF</a></li> <li><a href="/wiki/QOI_(image_format)" title="QOI (image format)">QOI</a></li> <li><a href="/wiki/QuickTime_VR" title="QuickTime VR">QTVR</a></li> <li><a href="/wiki/Wireless_Application_Protocol_Bitmap_Format" title="Wireless Application Protocol Bitmap Format">WBMP</a></li> <li><a href="/wiki/WebP" title="WebP">WebP</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Digital_container_format" class="mw-redirect" title="Digital container format">Containers</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">IEC</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/MPEG_elementary_stream" title="MPEG elementary stream">MPEG-ES</a> <ul><li><a href="/wiki/Packetized_elementary_stream" title="Packetized elementary stream">MPEG-PES</a></li></ul></li> <li><a href="/wiki/MPEG_program_stream" title="MPEG program stream">MPEG-PS</a></li> <li><a href="/wiki/MPEG_transport_stream" title="MPEG transport stream">MPEG-TS</a></li> <li><a href="/wiki/ISO/IEC_base_media_file_format" class="mw-redirect" title="ISO/IEC base media file format">ISO/IEC base media file format</a></li> <li><a href="/wiki/MPEG-4_Part_14" class="mw-redirect" title="MPEG-4 Part 14">MPEG-4 Part 14</a> (MP4)</li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">Motion JPEG 2000</a></li> <li><a href="/wiki/MPEG-21" title="MPEG-21">MPEG-21 Part 9</a></li> <li><a href="/wiki/MPEG_media_transport" title="MPEG media transport">MPEG media transport</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/ITU-T" title="ITU-T">ITU-T</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/MPEG-2#Systems" title="MPEG-2">H.222.0</a></li> <li><a href="/wiki/Motion_JPEG_2000" title="Motion JPEG 2000">T.802</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Internet_Engineering_Task_Force" title="Internet Engineering Task Force">IETF</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Real-time_Transport_Protocol" title="Real-time Transport Protocol">RTP</a></li> <li><a href="/wiki/Ogg" title="Ogg">Ogg</a></li> <li><a href="/wiki/Matroska" title="Matroska">Matroska</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em"><a href="/wiki/Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">SMPTE</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/General_Exchange_Format" title="General Exchange Format">GXF</a></li> <li><a href="/wiki/Material_Exchange_Format" title="Material Exchange Format">MXF</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:5em">Others</th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/3GP_and_3G2" title="3GP and 3G2">3GP and 3G2</a></li> <li><a href="/wiki/AMV_video_format" title="AMV video format">AMV</a></li> <li><a href="/wiki/Advanced_Systems_Format" title="Advanced Systems Format">ASF</a></li> <li><a href="/wiki/Audio_Interchange_File_Format" title="Audio Interchange File Format">AIFF</a></li> <li><a href="/wiki/Audio_Video_Interleave" title="Audio Video Interleave">AVI</a></li> <li><a href="/wiki/Au_file_format" title="Au file format">AU</a></li> <li><a href="/wiki/Better_Portable_Graphics" title="Better Portable Graphics">BPG</a></li> <li><a href="/wiki/Bink_Video" title="Bink Video">Bink</a> <ul><li><a href="/wiki/Smacker_video" title="Smacker video">Smacker</a></li></ul></li> <li><a href="/wiki/BMP_file_format" title="BMP file format">BMP</a></li> <li><a href="/wiki/DivX#DivX_Media_Format_(DMF)" title="DivX">DivX Media Format</a></li> <li><a href="/wiki/Enhanced_VOB" title="Enhanced VOB">EVO</a></li> <li><a href="/wiki/Flash_Video" title="Flash Video">Flash Video</a></li> <li><a href="/wiki/High_Efficiency_Image_File_Format" title="High Efficiency Image File Format">HEIF</a></li> <li><a href="/wiki/Interchange_File_Format" title="Interchange File Format">IFF</a></li> <li><a href="/wiki/.m2ts" title=".m2ts">M2TS</a></li> <li><a href="/wiki/Matroska" title="Matroska">Matroska</a> <ul><li><a href="/wiki/WebM" title="WebM">WebM</a></li></ul></li> <li><a href="/wiki/QuickTime_File_Format" title="QuickTime File Format">QuickTime File Format</a></li> <li><a href="/wiki/RatDVD" title="RatDVD">RatDVD</a></li> <li><a href="/wiki/RealMedia" title="RealMedia">RealMedia</a></li> <li><a href="/wiki/Resource_Interchange_File_Format" title="Resource Interchange File Format">RIFF</a> <ul><li><a href="/wiki/WAV" title="WAV">WAV</a></li></ul></li> <li><a href="/wiki/MOD_and_TOD" title="MOD and TOD">MOD and TOD</a></li> <li><a href="/wiki/VOB" title="VOB">VOB, IFO and BUP</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Collaborations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/NETVC" title="NETVC">NETVC</a></li> <li><a href="/wiki/MPEG_LA" title="MPEG LA">MPEG LA</a></li> <li><a href="/wiki/Alliance_for_Open_Media" title="Alliance for Open Media">Alliance for Open Media</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Data_compression" title="Data compression">Methods</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Entropy_encoding" class="mw-redirect" title="Entropy encoding">Entropy</a> <ul><li><a href="/wiki/Arithmetic_coding" title="Arithmetic coding">Arithmetic</a></li> <li><a href="/wiki/Huffman_coding" title="Huffman coding">Huffman</a></li> <li><a href="/wiki/Modified_Huffman_coding" title="Modified Huffman coding">Modified</a></li></ul></li> <li><a href="/wiki/Linear_predictive_coding" title="Linear predictive coding">LPC</a> <ul><li><a href="/wiki/Algebraic_code-excited_linear_prediction" title="Algebraic code-excited linear prediction">ACELP</a></li> <li><a href="/wiki/Code-excited_linear_prediction" title="Code-excited linear prediction">CELP</a></li> <li><a href="/wiki/Line_spectral_pairs" title="Line spectral pairs">LSP</a></li> <li><a href="/wiki/Warped_linear_predictive_coding" title="Warped linear predictive coding">WLPC</a></li></ul></li> <li><a href="/wiki/Lossless_compression" title="Lossless compression">Lossless</a></li> <li><a href="/wiki/Lossy_compression" title="Lossy compression">Lossy</a></li> <li><a href="/wiki/LZ77_and_LZ78" title="LZ77 and LZ78">LZ</a> <ul><li><a href="/wiki/DEFLATE" class="mw-redirect" title="DEFLATE">DEFLATE</a></li> <li><a href="/wiki/Lempel%E2%80%93Ziv%E2%80%93Welch" title="Lempel–Ziv–Welch">LZW</a></li></ul></li> <li><a href="/wiki/Pulse-code_modulation" title="Pulse-code modulation">PCM</a> <ul><li><a href="/wiki/A-law_algorithm" title="A-law algorithm">A-law</a></li> <li><a href="/wiki/%CE%9C-law_algorithm" title="Μ-law algorithm">µ-law</a></li> <li><a href="/wiki/Adaptive_differential_pulse-code_modulation" title="Adaptive differential pulse-code modulation">ADPCM</a></li> <li><a href="/wiki/Differential_pulse-code_modulation" title="Differential pulse-code modulation">DPCM</a></li></ul></li> <li><a href="/wiki/Transform_coding" title="Transform coding">Transforms</a> <ul><li><a href="/wiki/Discrete_cosine_transform" title="Discrete cosine transform">DCT</a></li> <li><a href="/wiki/Fast_Fourier_transform" title="Fast Fourier transform">FFT</a></li> <li><a href="/wiki/Modified_discrete_cosine_transform" title="Modified discrete cosine transform">MDCT</a></li> <li><a href="/wiki/Wavelet" title="Wavelet">Wavelet</a> <ul><li><a href="/wiki/Daubechies_wavelet" title="Daubechies wavelet">Daubechies</a></li> <li><a href="/wiki/Discrete_wavelet_transform" title="Discrete wavelet transform">DWT</a></li></ul></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Lists</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Comparison_of_audio_coding_formats" title="Comparison of audio coding formats">Comparison of audio coding formats</a></li> <li><a href="/wiki/Comparison_of_video_codecs" title="Comparison of video codecs">Comparison of video codecs</a></li> <li><a href="/wiki/List_of_codecs" title="List of codecs">List of codecs</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>See <a href="/wiki/Template:Compression_methods" title="Template:Compression methods">Compression methods</a> for techniques and <a href="/wiki/Template:Compression_software" title="Template:Compression software">Compression software</a> for codecs</div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="ITU_recommendations_(standards)" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:ITU_standards" title="Template:ITU standards"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:ITU_standards" title="Template talk:ITU standards"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:ITU_standards" title="Special:EditPage/Template:ITU standards"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="ITU_recommendations_(standards)" style="font-size:114%;margin:0 4em"><a href="/wiki/International_Telecommunication_Union" title="International Telecommunication Union">ITU</a> recommendations (standards)</div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><i><u>Lists:</u></i> <a href="/wiki/List_of_ITU-T_V-series_recommendations" title="List of ITU-T V-series recommendations">List of ITU-T V-series recommendations</a></li> <li><a href="/wiki/List_of_ITU_letter_codes" title="List of ITU letter codes">List of ITU letter codes</a><br /><i><u>Categories:</u></i> <a href="/wiki/Category:ITU-R_recommendations" title="Category:ITU-R recommendations">Category:ITU-R recommendations</a></li> <li><a href="/wiki/Category:ITU-T_recommendations" title="Category:ITU-T recommendations">Category:ITU-T recommendations</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">G series (ITU-T)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/G.114" class="mw-redirect" title="G.114">G.114</a></li> <li><a href="/wiki/G.165" title="G.165">G.165</a></li> <li><a href="/wiki/G.703" title="G.703">G.703</a></li> <li><a href="/w/index.php?title=G.704&action=edit&redlink=1" class="new" title="G.704 (page does not exist)">G.704</a></li> <li><a href="/wiki/G.706" title="G.706">G.706</a></li> <li><a href="/wiki/Synchronous_optical_networking" title="Synchronous optical networking">G.707</a></li> <li><a href="/wiki/G.709" title="G.709">G.709</a></li> <li><a href="/wiki/G.711" title="G.711">G.711</a></li> <li><a href="/wiki/G.718" title="G.718">G.718</a></li> <li><a href="/wiki/G.719" title="G.719">G.719</a></li> <li><a href="/wiki/G.722" title="G.722">G.722</a></li> <li><a href="/wiki/G.722.1" title="G.722.1">G.722.1</a></li> <li><a href="/wiki/Adaptive_Multi-Rate_Wideband" title="Adaptive Multi-Rate Wideband">G.722.2</a></li> <li><a href="/wiki/G.729.1" title="G.729.1">G.729.1</a></li> <li><a href="/wiki/G.723" title="G.723">G.723</a></li> <li><a href="/wiki/G.723.1" title="G.723.1">G.723.1</a></li> <li><a href="/wiki/G.726" title="G.726">G.726</a></li> <li><a href="/wiki/G.728" title="G.728">G.728</a></li> <li><a href="/wiki/G.729" title="G.729">G.729</a></li> <li><a href="/wiki/G.783" title="G.783">G.783</a></li> <li><a href="/wiki/G.798" class="mw-redirect" title="G.798">G.798</a></li> <li><a href="/w/index.php?title=G.806&action=edit&redlink=1" class="new" title="G.806 (page does not exist)">G.806</a></li> <li><a href="/wiki/G.811" title="G.811">G.811</a></li> <li><a href="/wiki/G.983" title="G.983">G.983</a></li> <li><a href="/wiki/G.984" class="mw-redirect" title="G.984">G.984</a></li> <li><a href="/wiki/G.987" class="mw-redirect" title="G.987">G.987</a></li> <li><a href="/wiki/G.988" title="G.988">G.988</a></li> <li><a href="/wiki/High-bit-rate_digital_subscriber_line" title="High-bit-rate digital subscriber line">G.991.1</a></li> <li><a href="/wiki/Single-pair_high-speed_digital_subscriber_line" title="Single-pair high-speed digital subscriber line">G.991.2</a></li> <li><a href="/wiki/ITU_G.992.1" class="mw-redirect" title="ITU G.992.1">G.992.1</a></li> <li><a href="/wiki/ITU_G.992.2" class="mw-redirect" title="ITU G.992.2">G.992.2</a></li> <li><a href="/wiki/ITU_G.992.3" class="mw-redirect" title="ITU G.992.3">G.992.3</a> <ul><li><a href="/wiki/ITU_G.992.3_Annex_J" class="mw-redirect" title="ITU G.992.3 Annex J">Annex J</a></li> <li><a href="/wiki/ITU_G.992.3_Annex_L" class="mw-redirect" title="ITU G.992.3 Annex L">Annex L</a></li></ul></li> <li><a href="/wiki/ITU_G.992.4" class="mw-redirect" title="ITU G.992.4">G.992.4</a></li> <li><a href="/wiki/ITU_G.992.5" class="mw-redirect" title="ITU G.992.5">G.992.5</a> <ul><li><a href="/wiki/ITU_G.992.5_Annex_M" class="mw-redirect" title="ITU G.992.5 Annex M">Annex M</a></li></ul></li> <li><a href="/wiki/Very-high-bit-rate_digital_subscriber_line" class="mw-redirect" title="Very-high-bit-rate digital subscriber line">G.993.1</a></li> <li><a href="/wiki/ITU_G.993.2" class="mw-redirect" title="ITU G.993.2">G.993.2</a></li> <li><a href="/wiki/Generic_Framing_Procedure" title="Generic Framing Procedure">G.7041</a></li> <li><a href="/wiki/Link_Capacity_Adjustment_Scheme" title="Link Capacity Adjustment Scheme">G.7042</a></li> <li><a href="/w/index.php?title=G.7043&action=edit&redlink=1" class="new" title="G.7043 (page does not exist)">G.7043</a></li> <li><a href="/wiki/Synchronous_Ethernet" title="Synchronous Ethernet">G.8262</a></li> <li><a href="/wiki/G.fast" title="G.fast">G.9700, G.9701, G.9710 and G.9711</a></li> <li><a href="/wiki/G.hn" title="G.hn">G.9960</a></li> <li><a href="/wiki/ITU_G.9970" class="mw-redirect" title="ITU G.9970">G.9970</a></li> <li><a href="/wiki/ITU_G.9972" class="mw-redirect" title="ITU G.9972">G.9972</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">H series (ITU-T)</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/H.222.0" class="mw-redirect" title="H.222.0">H.222.0</a></li> <li><a href="/wiki/H.225.0" class="mw-redirect" title="H.225.0">H.225.0</a></li> <li><a href="/wiki/H.235" title="H.235">H.235</a></li> <li><a href="/wiki/H.239" title="H.239">H.239</a></li> <li><a href="/wiki/H.241" title="H.241">H.241</a></li> <li><a href="/wiki/H.245" title="H.245">H.245</a></li> <li><a href="/wiki/H.248" title="H.248">H.248</a></li> <li><a href="/wiki/H.261" title="H.261">H.261</a></li> <li><a href="/wiki/H.262/MPEG-2_Part_2" title="H.262/MPEG-2 Part 2">H.262/MPEG-2 Video</a></li> <li><a href="/wiki/H.263" title="H.263">H.263</a></li> <li><a href="/wiki/Advanced_Video_Coding" title="Advanced Video Coding">H.264/MPEG-4 AVC</a></li> <li><a href="/wiki/High_Efficiency_Video_Coding" title="High Efficiency Video Coding">H.265/MPEG-H HEVC</a></li> <li><a href="/wiki/Versatile_Video_Coding" title="Versatile Video Coding">H.266/MPEG-I VVC</a></li> <li><a href="/wiki/H.320" title="H.320">H.320</a></li> <li><a class="mw-selflink selflink">H.323</a></li> <li><a href="/wiki/H.323_Gatekeeper" title="H.323 Gatekeeper">H.323 Gatekeeper</a></li> <li><a href="/wiki/H.324" title="H.324">H.324</a></li> <li><a href="/wiki/H.450" title="H.450">H.450</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/List_of_ITU-T_V-series_recommendations" title="List of ITU-T V-series recommendations">V series</a> (ITU-T)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/RS-423" title="RS-423">V.10</a></li> <li><a href="/wiki/RS-422" title="RS-422">V.11</a></li> <li><a href="/wiki/ITU-T_V.23" title="ITU-T V.23">V.23</a></li> <li><a href="/wiki/RS-232" title="RS-232">V.24</a></li> <li><a href="/wiki/ITU-T_V.92" title="ITU-T V.92">V.92</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">ITU-R</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ITU-R_468_noise_weighting" title="ITU-R 468 noise weighting">ITU-R 468 noise weighting</a></li> <li><a href="/wiki/ITU-R_BS.1534-1" class="mw-redirect" title="ITU-R BS.1534-1">ITU-R BS.1534-1</a></li> <li><a href="/wiki/ITU-R_BT.1304" class="mw-redirect" title="ITU-R BT.1304">ITU-R BT.1304</a></li> <li><a href="/wiki/ITU-R_BT.470-6" class="mw-redirect" title="ITU-R BT.470-6">ITU-R BT.470-6</a></li> <li><a href="/wiki/ITU-R_BT.470-7" class="mw-redirect" title="ITU-R BT.470-7">ITU-R BT.470-7</a></li> <li><a href="/wiki/ITU-R_BT.601" class="mw-redirect" title="ITU-R BT.601">ITU-R BT.601</a></li> <li><a href="/wiki/ITU-R_BT.709" class="mw-redirect" title="ITU-R BT.709">ITU-R BT.709</a></li> <li><a href="/wiki/ITU-R_BT.2020" class="mw-redirect" title="ITU-R BT.2020">ITU-R BT.2020</a></li> <li><a href="/wiki/Rec._2100" title="Rec. 2100">ITU-R BT.2100</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><i>See also:</i> <span class="plainlinks"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Special:PrefixIndex&prefix=ITU&namespace=0">All articles beginning with "ITU"</a></span></div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=H.323&oldid=1214242721">https://en.wikipedia.org/w/index.php?title=H.323&oldid=1214242721</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:VoIP_protocols" title="Category:VoIP protocols">VoIP protocols</a></li><li><a href="/wiki/Category:Videotelephony" title="Category:Videotelephony">Videotelephony</a></li><li><a href="/wiki/Category:ITU-T_recommendations" title="Category:ITU-T recommendations">ITU-T recommendations</a></li><li><a href="/wiki/Category:ITU-T_H_Series_Recommendations" title="Category:ITU-T H Series Recommendations">ITU-T H Series Recommendations</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:CS1_maint:_unfit_URL" title="Category:CS1 maint: unfit URL">CS1 maint: unfit URL</a></li><li><a href="/wiki/Category:Wikipedia_articles_needing_factual_verification_from_March_2011" title="Category:Wikipedia articles needing factual verification from March 2011">Wikipedia articles needing factual verification from March 2011</a></li><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_is_different_from_Wikidata" title="Category:Short description is different from Wikidata">Short description is different from Wikidata</a></li><li><a href="/wiki/Category:Articles_lacking_in-text_citations_from_April_2020" title="Category:Articles lacking in-text citations from April 2020">Articles lacking in-text citations from April 2020</a></li><li><a href="/wiki/Category:All_articles_lacking_in-text_citations" title="Category:All articles lacking in-text citations">All articles lacking in-text citations</a></li><li><a href="/wiki/Category:Wikipedia_articles_in_need_of_updating_from_June_2021" title="Category:Wikipedia articles in need of updating from June 2021">Wikipedia articles in need of updating from June 2021</a></li><li><a href="/wiki/Category:All_Wikipedia_articles_in_need_of_updating" title="Category:All Wikipedia articles in need of updating">All Wikipedia articles in need of updating</a></li><li><a href="/wiki/Category:Articles_with_multiple_maintenance_issues" title="Category:Articles with multiple maintenance issues">Articles with multiple maintenance issues</a></li><li><a href="/wiki/Category:All_articles_with_unsourced_statements" title="Category:All articles with unsourced statements">All articles with unsourced statements</a></li><li><a href="/wiki/Category:Articles_with_unsourced_statements_from_June_2008" title="Category:Articles with unsourced statements from June 2008">Articles with unsourced statements from June 2008</a></li><li><a href="/wiki/Category:Articles_with_unsourced_statements_from_March_2009" title="Category:Articles with unsourced statements from March 2009">Articles with unsourced statements from March 2009</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 17 March 2024, at 19:39<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. By using this site, you agree to the <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use" class="extiw" title="foundation:Special:MyLanguage/Policy:Terms of Use">Terms of Use</a> and <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy" class="extiw" title="foundation:Special:MyLanguage/Policy:Privacy policy">Privacy Policy</a>. Wikipedia® is a registered trademark of the <a rel="nofollow" class="external text" href="https://wikimediafoundation.org/">Wikimedia Foundation, Inc.</a>, a non-profit organization.</li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/Wikipedia:About">About Wikipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wikipedia:General_disclaimer">Disclaimers</a></li> <li id="footer-places-contact"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us">Contact Wikipedia</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Code of Conduct</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Developers</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/en.wikipedia.org">Statistics</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Cookie statement</a></li> <li id="footer-places-mobileview"><a href="//en.m.wikipedia.org/w/index.php?title=H.323&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Mobile view</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/static/images/footer/wikimedia-button.svg" width="84" height="29" alt="Wikimedia Foundation" loading="lazy"></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/w/resources/assets/poweredby_mediawiki.svg" alt="Powered by MediaWiki" width="88" height="31" loading="lazy"></a></li> </ul> </footer> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-f69cdc8f6-nfzrr","wgBackendResponseTime":145,"wgPageParseReport":{"limitreport":{"cputime":"0.714","walltime":"1.036","ppvisitednodes":{"value":3533,"limit":1000000},"postexpandincludesize":{"value":135078,"limit":2097152},"templateargumentsize":{"value":11623,"limit":2097152},"expansiondepth":{"value":20,"limit":100},"expensivefunctioncount":{"value":6,"limit":500},"unstrip-depth":{"value":1,"limit":20},"unstrip-size":{"value":45164,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 690.117 1 -total"," 24.96% 172.260 1 Template:Reflist"," 18.37% 126.762 4 Template:Cite_web"," 18.06% 124.661 6 Template:Navbox"," 16.44% 113.477 1 Template:Compression_formats"," 14.89% 102.784 1 Template:Multiple_issues"," 12.32% 85.013 1 Template:Infobox_technology_standard"," 12.15% 83.868 1 Template:Short_description"," 11.57% 79.873 1 Template:Infobox"," 11.09% 76.540 7 Template:Fix"]},"scribunto":{"limitreport-timeusage":{"value":"0.382","limit":"10.000"},"limitreport-memusage":{"value":6275400,"limit":52428800}},"cachereport":{"origin":"mw-web.codfw.main-f69cdc8f6-7zkrf","timestamp":"20241122150023","ttl":723586,"transientcontent":true}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"H.323","url":"https:\/\/en.wikipedia.org\/wiki\/H.323","sameAs":"http:\/\/www.wikidata.org\/entity\/Q1128649","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q1128649","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2002-07-30T09:11:01Z","dateModified":"2024-03-17T19:39:51Z","image":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/d\/d1\/H323_1gk.gif","headline":"communications protocol"}</script> </body> </html>