The Session Initiation Protocol (SIP): an Evolutionary Study Salman Abdul Baset, Vijay K
JOURNAL OF COMMUNICATIONS, VOL. 7, NO. 2, FEBRUARY 2012 89 The Session Initiation Protocol (SIP): An Evolutionary Study Salman Abdul Baset, Vijay K. Gurbani, Alan B. Johnston, Hadriel Kaplan, Brian Rosen and Jonathan D. Rosenberg Abstract— The Session Initiation Protocol (SIP) was devel- and control (rewind, forward) multimedia streams from oped to control multi-media sessions on the Internet. Shortly a media server. RTP is a protocol for transporting real- after its debut as a standard in 1999, SIP was adopted time data such as audio, video, or instant messages. In by the 3rd Generation Partnership Project (3GPP) as the preferred signaling protocol for the Internet Multimedia 1996, these were the protocols that powered the Internet Subsystem (IMS). This adoption provided a boost to the multicast backbone (MBONE) for loosely coupled multi- nascent protocol as traditional telecommunication services cast conferences. SIP was introduced into this mix. were interpreted in the context of the new protocol and In early 1996, there were two protocols competing for as SIP introduced richer services in the form of instant session establishment in the IETF: the Session Invitation messaging and rich presence to traditional telephony. In this paper, we study the evolution of the protocol from its Protocol and the Simple Conference Invitation Protocol roots to its use in operational networks today and the issues (SCIP). Session Invitation Protocol was responsible only it faces in such networks. We also provide a glimpse to the for setting up the session and providing rudimentary continued progression of SIP in Peer-to-Peer (P2P) networks capability negotiation; once the session had started, it was and take a critical look at where SIP has succeeded, and not used at all [7].
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