[OpenSIPS-Users] question on call handling.

Ben Newlin Ben.Newlin at genesys.com
Thu Oct 21 17:31:40 EST 2021


Bogdan,

Actually I was referring to these parts:

If the initial offer is in an INVITE, the answer MUST be in a
reliable non-failure message from UAS back to UAC which is
correlated to that INVITE.  For this specification, that is
only the final 2xx response to that INVITE.  That same exact
answer MAY also be placed in any provisional responses sent
prior to the answer.  The UAC MUST treat the first session
description it receives as the answer, and MUST ignore any
session descriptions in subsequent responses to the initial
INVITE.

…

Concretely, the above rules specify two exchanges for UAs compliant
to this specification alone - the offer is in the INVITE, and the
answer in the 2xx (and possibly in a 1xx as well, with the same
value), or the offer is in the 2xx, and the answer is in the ACK.
All user agents that support INVITE MUST support these two exchanges.

Ben Newlin

From: Bogdan-Andrei Iancu <bogdan at opensips.org>
Date: Wednesday, October 6, 2021 at 2:37 AM
To: OpenSIPS users mailling list <users at lists.opensips.org>, Ben Newlin <Ben.Newlin at genesys.com>
Subject: Re: [OpenSIPS-Users] question on call handling.
Hi Ben,

The paragraph you refer to is this one :

      o  After having sent or received an answer to the first offer, the

         UAC MAY generate subsequent offers in requests based on rules

         specified for that method, but only if it has received answers

         to any previous offers, and has not sent any offers to which it

         hasn't gotten an answer.

So the 200 must contain the same SDP as the 180 because there is no SDP replied back between the 180 and 200 ?

Regards,


Bogdan-Andrei Iancu



OpenSIPS Founder and Developer

  https://www.opensips-solutions.com<https://www.opensips-solutions.com>

OpenSIPS eBootcamp 2021

  https://opensips.org/training/OpenSIPS_eBootcamp_2021/<https://opensips.org/training/OpenSIPS_eBootcamp_2021>
On 10/1/21 5:41 PM, Ben Newlin wrote:
No, this is not allowed by the specification, though some devices do handle it.

https://datatracker.ietf.org/doc/html/rfc3261#section-13.2.1<https://datatracker.ietf.org/doc/html/rfc3261#section-13.2.1>

Ben Newlin

From: Users <users-bounces at lists.opensips.org><mailto:users-bounces at lists.opensips.org> on behalf of johan <johan at democon.be><mailto:johan at democon.be>
Date: Friday, October 1, 2021 at 10:35 AM
To: OpenSIPS users mailling list <users at lists.opensips.org><mailto:users at lists.opensips.org>
Subject: [OpenSIPS-Users] question on call handling.
Dears,


this is more a general sip question.  when establishing a dialog is it
then allowed to change the sdp that you have sent in 183 to somehting
else in 200 Ok ?


wkr,


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