Thanks Michael, I was searching for similar questions and I found the following query by Christer, [EMAIL PROTECTED]:
--------------------------------------- Hi, Chapter of 3261 says: "However, if the To header field in the request did not contain a tag, the URI in the To header field in the response MUST equal the URI in the To header field; additionally, the UAS MUST add a tag to the To header field in the response (with the exception of the 100 (Trying) response, in which a tag MAY be present). This serves to identify the UAS that is responding, possibly resulting in a component of a dialog ID." My question is: is there a reason why a final error response to an initial INVITE, for which NO provisional responses have been sent (ie no dialog has been established), must contain a To tag? Regards, Christer --------------------------------------- I was not able to find answers to this query. Regards, Sunil -----Original Message----- From: Michael Procter [mailto:[EMAIL PROTECTED] Sent: Thursday, November 13, 2008 7:32 PM To: Sunil Bhagat (WT01 - Telecom Equipment) Cc: [email protected] Subject: Re: [Sip] Is To-tag in non 2xx response mandatory [EMAIL PROTECTED] wrote: > Hi, > > Should a to-tag be added to a 487 response to an initial INVITE? Even if 180 Ringing has not been sent? > > Regards, > > Sunil > Yes. RFC 3261 Section 8.2.6.2: additionally, the UAS MUST add a tag to the To header field in the response (with the exception of the 100 (Trying) response, in which a tag MAY be present) Regards, Michael PS Looking in the footer for this list shows: > Sip mailing list https://www.ietf.org/mailman/listinfo/sip > This list is for NEW development of the core SIP Protocol > Use [EMAIL PROTECTED] for questions on current sip > Use [EMAIL PROTECTED] for new developments on the application of sip Maybe you should consider sip-implementors for further questions like this. _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
