[OpenSIPS-Users] question on call handling.

Calvin Ellison calvin.ellison at voxox.com
Thu Oct 21 21:03:48 EST 2021


Johan, is there also a PRACK happening in this call flow, but omitted from
your diagram? The SDP offer/answer model is extended a bit by reliable
provisional response messages.

The Offer/Answer Model and PRACK
https://datatracker.ietf.org/doc/html/rfc3262#section-5



Calvin Ellison

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On Fri, Oct 1, 2021 at 8:07 AM johan <johan at democon.be> wrote:

> Scenario is this
>
>
> A  ---> OPENSIPS and rtpengine -----> B
>
>     INV     ->                                 >   INV
>
>     183 sdp  <                              <183 sdp
>
>                                                   <  480
>
>
> -------------------------------------------------> Voicemail
>
>                                                      > INV
>
>                                                       < 200 with diff sdp
>
>     200 with diff sdp <
>
> would giving rtpengine the port latching option fix this ?
>
>
> wkr,
> On 1/10/2021 16:41, 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
>
>
>
> Ben Newlin
>
>
>
> *From: *Users <users-bounces at lists.opensips.org>
> <users-bounces at lists.opensips.org> on behalf of johan <johan at democon.be>
> <johan at democon.be>
> *Date: *Friday, October 1, 2021 at 10:35 AM
> *To: *OpenSIPS users mailling list <users at lists.opensips.org>
> <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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