Source : Free On-Line Dictionary of Computing

Session Initiation Protocol
     
         (SIP) A very simple text-based application-layer
        control {protocol}.  It creates, modifies, and terminates
        {sessions} with one or more participants.  Such sessions
        include {Internet telephony} and {multimedia} conferences.
     
        It is described in {RFC 2543}.
     
        (2000-05-31)