ZyXEL Communications ZyWall 110 User Manual page 459

Chapter 15 ALG
H.323
H.323 is a standard teleconferencing protocol suite that provides audio, data and video conferencing.
It allows for real-time point-to-point and multipoint communication between client computers over a
packet-based network that does not provide a guaranteed quality of service. NetMeeting uses H.323.
SIP
The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol that handles the
setting up, altering and tearing down of voice and multimedia sessions over the Internet. SIP is used in
VoIP (Voice over IP), the sending of voice signals over the Internet Protocol.
SIP signaling is separate from the media for which it handles sessions. The media that is exchanged
during the session can use a different path from that of the signaling. SIP handles telephone calls and
can interface with traditional circuit-switched telephone networks.
RTP
When you make a VoIP call using H.323 or SIP, the RTP (Real time Transport Protocol) is used to handle
voice data transfer. See RFC 1889 for details on RTP.
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