Sip Overview - 3Com V7122 User Manual

Figure 1 illustrates typical gateway applications over VoIP network.
Typical Gateway Application
Figure 1

SIP Overview

SIP is an application-layer control (signaling) protocol used on the gateway for creating,
modifying, and terminating sessions with one or more participants. These sessions can
include Internet telephone calls, media announcements and conferences.
SIP invitations are used to create sessions and carry session descriptions that enable
participants to agree on a set of compatible media types. SIP uses elements called proxy
servers to help route requests to the user's current location, authenticate and authorize users
for services, implement provider call-routing policies and provide features to users.
SIP also provides a registration function that enables users to upload their current locations
for use by proxy servers. SIP, on the gateway, complies with the IETF (Internet Engineering
Task Force) RFC 3261 (see www.ietf.org/rfc/rfc3261.txt?number=3261).
22
V7122 GatewayUser Guide