ZyXEL Communications 200 Series - Manual (Page 331)

Chapter 18 ALG
ZyWALL USG 100/200 Series User’s Guide
331
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.