Re: Is To-tag in non 2xx response mandatory

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