Hi Arun,
If you add To-Tag in INVITE, then It will be a re-invite. If the dialog is already established then UAC can send invite with to-tag. UAS will generate to tag while sending response(18x/2xx) for INVITE. 1. No to-Tag in INVITE WHY? Here your question is like. Why there is no to-tag in Initial INVITE request? The answer will be, UAC will responsible for local tag(from tag). Then remote tag(To-Tag) will be generated by user agent server(UAS). Note: the same answer Amit also mentioned clearly with RFC. Thanks, Pradeep > Date: Tue, 5 Aug 2014 13:13:59 +0530 > From: arun.taga...@gmail.com > To: amit2.si...@aricent.com > CC: sip-implementors@lists.cs.columbia.edu > Subject: Re: [Sip-implementors] : No To-Tag in INVITE why? > > Hi Amit, > > Thank you for your Response > Thanks for explaining the dot i was having with respect to the To-Tag in > the INVITE request. > > Thank you, > With Regards > Arun A. Tagare > > > On Tue, Aug 5, 2014 at 12:25 PM, Amit Kumar Singh <amit2.si...@aricent.com> > wrote: > > > Hi, > > > > Section 19.3 of RFC 3261 states the following: > > > > " The tag parameter is used in the To and From header fields of SIP > > messages. It serves as a general mechanism to identify a dialog, which is > > the combination of the Call-ID along with two tags, one from each > > participant in the dialog. When a UA sends a request outside of a dialog, > > it contains a From tag only, providing "half" of the dialog ID. The dialog > > is completed from the response(s), each of which contributes the second > > half in the To header field. The forking of SIP requests means that > > multiple dialogs can be established from a single request. This also > > explains the need for the two-sided dialog identifier; without a > > contribution from the recipients, the originator could not disambiguate the > > multiple dialogs established from a single request." > > > > As the RFC clearly states that the dialog is completed from the responses > > thus it should be the UAS to generate the To Tag in the response not the > > UAC. In the case of Forking of single SIP request, to avoid the ambiguity > > in multiple dialogs contribution from the recipients (UAS), in our case To > > Tag, is necessary. > > > > Regards, > > Amit Kumar Singh > > amit2.si...@aricent.com > > > > > > > > -----Original Message----- > > From: sip-implementors-boun...@lists.cs.columbia.edu [mailto: > > sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Arun Tagare > > Sent: Tuesday, August 05, 2014 11:45 AM > > To: sip-implementors@lists.cs.columbia.edu > > Subject: [Sip-implementors] : No To-Tag in INVITE why? > > > > Hi All, > > > > Can any one explain me > > Why there is no To-Tag in the INVITE Request? > > > > And what happens if i add To-Tag in the INVITE Request? > > > > -- > > > > With Regards > > > > Arun A. Tagare > > +91 9449 029729 > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > > "DISCLAIMER: This message is proprietary to Aricent and is intended solely > > for the use of the individual to whom it is addressed. It may contain > > privileged or confidential information and should not be circulated or used > > for any purpose other than for what it is intended. If you have received > > this message in error, please notify the originator immediately. If you are > > not the intended recipient, you are notified that you are strictly > > prohibited from using, copying, altering, or disclosing the contents of > > this message. Aricent accepts no responsibility for loss or damage arising > > from the use of the information transmitted by this email including damage > > from virus." > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > > > > > > -- > > With Regards > > Arun A. Tagare > +91 9449 029729 > _______________________________________________ > 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
