Chapter 4 - Session Control on the Internet

Many think that the most important component of the signaling plane is the protocol that performs session control. The protocol chosen to perform this task in the IMS is the Session Initiation Protocol (SIP) (defined in RFC 3261 [286]). SIP was originally developed within the SIP working group in the IETF. Even though SIP was initially designed to invite users to existing multimedia conferences, today it is mainly used to create, modify and terminate multimedia sessions.