< communications , standard > The ITU-T standard for sending voice ( audio ) and video using IP on a LAN without QoS .
H.323 includes Q.931 for call setup, H.225 for call signalling, H.245 for exchanging terminal capabilities, RTP / RTCP for packet streaming, G.711 / G.712 for CODEC s, and several other protcols , many of which need to be negotiated to setup a simple voice call.
The complexity of H.323 has lead to the IETF proposing the simpler alternatives SIP and MGCP / Megaco .
(2003-11-30)