[SR-Users] To tags in 407 challenges

[Emmanuel BUU]

Le 2018-03-26 à 22:49, Alex Balashov a écrit :
> On Mon, Mar 26, 2018 at 10:27:35PM +0200, Henning Westerholt wrote:
>
>> I would think this is normal UAC/UAS behavior for SIP request handling:
>>
>> RFC 3261, sect. 8.2.6.2:
>> "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. "
> Honestly, in ten years of doing SIP, this is the first time I am
> confronting this question. I was accustomed to the notion that To tags
> are only added to a reply when it is desirable to form an early dialog
> (in the case of a non-100 1xx reply). But the passage you quote seems to
> settle it.
An additional question!
Does  second authenticated INVITE sent by UAC should also mention this 
to tag and the called UA should also accept it as part of the dialog id ?

Or does the second authenticated INVITE open a new dialog ?

Emmanuel