H.323 Protocl

H.323 is a protocol standard for multimedia communications. H.323 was designed to support real-time transfer of audio and video data over packet networks. The standard involve several different protocols outside specific aspects of Internet telephony. The International Telecommunication Union (ITU-T) maintains H.323 and these related standards. Most voice over IP (VoIP) applications utilizes H.323.
H.323 supports call setup, rip down and forward/transfer. Architectural basics of a H.323 based system are Terminals, Multipoint Control Units (MCUs), Gateways, an optional Gatekeeper and Border Elements. Different functions of H.323 run over either TCP or UDP. H.323 competes with the newer Session Initialization Protocol (SIP) another established standard often found in VoIP systems. A key feature of H.323 is Quality of Service. H.323 Technology allows real-time prioritization and traffic management constraint to be placed on the “best effort” packet release system like TCP/IP over Ethernet.