The Call-ID is obvious. The To tag helps handle forking situations. The From tag used to be optional during call setup. It became mandatory because a common issue was that devices and operators occasionally incorrectly classified re-INVITE as INVITE because the To tag was missing to help with the analysis.
> -----Original Message----- > From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip- > implementors-boun...@lists.cs.columbia.edu] On Behalf Of Harshith Mulky > Sent: Tuesday, October 27, 2015 8:20 AM > To: sip-implementors@lists.cs.columbia.edu > Subject: [Sip-implementors] Need of From/To Tag in SIP Dialog > > We all know a SIP dialog is complete when it comprises of Call-ID, From Tag > and the To Tag. > > Why do we have 3 different things to complete a Dialog when we could only > have Call-ID to complete a Dialog > > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
