Dialogic 6.2 - Manual (Page 244)

Understanding the SIP Protocol
November 2009 244
Understanding the SIP Protocol
You can use the Session Initiation Protocol (SIP), an
application-layer control (signaling) protocol, to create, modify, and
terminate sessions with one or more participants.
These sessions include internet telephone calls, multimedia
distribution, and multimedia conferences. SIP invitations used to
create sessions carry session descriptions that allow participants to
agree on a set of compatible media types. SIP makes use of elements
called proxy servers to help do the following:
„ Route requests to the user's current location
„ Authenticate and authorize users for services
„ Implement provider call-routing policies
„ Provide features to users.
SIP also provides a registration function that allows users to
upload their current locations for use by proxy servers.
SIP runs on top of several different transport protocols.
This section has the following sections:
„ Introduction to the SIP Protocol
„ Overview of SIP Functionality
„ SIP works with both IPv4 and IPv6.
Introduction to the SIP Protocol
There are many applications of the internet that require the creation
and management of a session (a session is considered to be an
exchange of data between an association of participants). The
implementation of these applications is complicated by the practices
of participants: users might move between endpoints, they might be
addressable by multiple names, and they might communicate in
several different media - sometimes simultaneously. (For copyright
information on this section, see page 255 .)