Basic functionality Addressing A SIP URI has the form of sip:username@host ■Registration allows one or more IP addresses to be associated with a particular SIP URI Session control invite another user agent to a particular session,to modify an ongoing session,and to terminate a sessionBasic functionality ◼ Addressing A SIP URI has the form of sip:username@host ◼ Registration allows one or more IP addresses to be associated with a particular SIP URI ◼ Session control invite another user agent to a particular session, to modify an ongoing session, and to terminate a session