H.323 IP telephony calls

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2, Windows Server 2008, Windows Server 2008 R2, Windows Server 8 Beta

H.323 IP telephony calls

The H.323 TAPI Service Provider provides H.323 version 1.0 support for TAPI-based programs. H.323 is a comprehensive (ITU-T) standard. It provides for multimedia communication over computer networks that do not provide a guaranteed quality of service, such as IP-based networks and the Internet. The H.323 standard enables any H.323-compliant terminal to operate with another.

H.323 encompasses call control, multimedia streaming, and bandwidth management for point-to-point calls and multipoint conferences over packet-switched networks. It is used for peer-to-peer, two-way delivery of audio and video phone data. It is designed to interact well with PSTN or Internet phone gateways. For conferencing, it works well for a moderate number of participants.

H.323 support defines the format for audio and video information and how audio and video information is packaged for transmission over the network. Standard audio and video codecs encode and decode input and output from audio and video sources to be communicated between nodes on a network.

TAPI 3.1 in Windows XP and the Windows Server 2003 family support H.323 gateways, gatekeepers, and proxies. To implement H.323 gateways and proxies with the H.323 TAPI Service Provider, see Specify an H.323 gateway or proxy. To implement H.323 gatekeepers, see Specify an H.323 gatekeeper.