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| Packet-based multimedia communications systems | |
 | |
| Status | In force |
|---|---|
| Year started | 1996 |
| Latest version | 8 March 2022 |
| Organization | ITU-T |
| Related standards | Q.931 |
| Website | www |
H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) that defines the protocols to provide audio-visual communication sessions on any packet network.[1] The H.323 standard addresses call signaling and control, multimedia transport and control, and bandwidth control for point-to-point and multi-point conferences.[2]
It is widely implemented[3] by voice and videoconferencing equipment manufacturers, is used within various Internet real-time applications such as GnuGK and NetMeeting and is widely deployed worldwide by service providers and enterprises for both voice and video services over IP networks.
It is a part of the ITU-T H.32x series of protocols, which also address multimedia communications over ISDN, the PSTN or SS7, and 3G mobile networks.
H.323 call signaling is based on the ITU-T Recommendation Q.931 protocol and is suited for transmitting calls across networks using a mixture of IP, PSTN, ISDN, and QSIG over ISDN. A call model, similar to the ISDN call model, eases the introduction of IP telephony into existing networks of ISDN-based PBX systems, including transitions to IP-based PBXs.
Within the context of H.323, an IP-based PBX might be a gatekeeper or other call control element which provides service to telephones or videophones. Such a device may provide or facilitate both basic services and supplementary services, such as call transfer, park, pick-up, and hold.
- ^ "H.323: Packet-based multimedia communications systems". www.itu.int. Archived from the original on 2021-04-29. Retrieved 2021-04-29.
- ^ Davidson, Jonathan; James Peters; Jim Peters; Brian Gracely (2000). "H.323". Voice over IP fundamentals. Cisco Press. pp. 229–230. ISBN 978-1-57870-168-1.
- ^ "H.323 Products & Services". Archived from the original on 15 May 2016.
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