27 Mar
2018
27 Mar
'18
3:30 p.m.
Le 2018-03-26 à 22:49, Alex Balashov a écrit :
On Mon, Mar 26, 2018 at 10:27:35PM +0200, Henning
Westerholt wrote:
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
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.