RFC - 2543

SIP: Session Initiation Protocol

Original:	ftp://ftp.isi.edu/in-notes/rfc2543.txt
Authors:	M. Handley [ACIRI], H. Schulzrinne [Columbia U.], E. Schooler [Cal Tech], J. Rosenberg [Bell Labs]
Date:	March 1999
Category:	Informational
This specification has been !!! obsoleted !!!

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Obsoleted by:
RFC-3265prop	Session Initiation Protocol (SIP)-Specific Event Notification
RFC-3264prop	An Offer/Answer Model with Session Description Protocol (SDP)
RFC-3263prop	Session Initiation Protocol (SIP): Locating SIP Servers
RFC-3262prop	Reliability of Provisional Responses in Session Initiation Protocol (SIP)
RFC-3261prop	SIP: Session Initiation Protocol (Updated by RFC-3265prop, RFC-3853prop, RFC-4320prop)

Referred by:	47 RFC
Refers to:	28 RFC

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Status

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1999). All Rights Reserved.

IESG Note

The IESG intends to charter, in the near future, one or more working groups to produce standards for "name lookup", where such names would include electronic mail addresses and telephone numbers, and the result of such a lookup would be a list of attributes and characteristics of the user or terminal associated with the name. Groups which are in need of a "name lookup" protocol should follow the development of these new working groups rather than using SIP for this function. In addition it is anticipated that SIP will migrate towards using such protocols, and SIP implementors are advised to monitor these efforts.

Abstract

The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants. These sessions include Internet multimedia conferences, Internet telephone calls and multimedia distribution. Members in a session can communicate via multicast or via a mesh of unicast relations, or a combination of these.

SIP invitations used to create sessions carry session descriptions which allow participants to agree on a set of compatible media types. SIP supports user mobility by proxying and redirecting requests to the user's current location. Users can register their current location. SIP is not tied to any particular conference control protocol. SIP is designed to be independent of the lower-layer transport protocol and can be extended with additional capabilities.

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