We've run into an issue again, where a provider won't accept re-INVITEs for session refresh where the SDP version counter hasn't been incremented. Has there been any work on this or should I open an issue at github to make this issue more visible?

Thanks!
George

On Fri, 4 May 2018 at 17:51, Richard Fuchs <rfuchs@sipwise.com> wrote:
On 04/11/2018 09:28 AM, George Diamantopoulos wrote:
> Hello all,
>
> I have the following issue (I think) with RTP engine. An INVITE comes
> in, and rtpengine will rewrite the SDP accordingly, as configured in
> kamailio.cfg. After some time a reINVITE is sent out in the opposite
> direction, for session refresh purposes. As I use rtcp-mux-offer in
> kamailio.cfg for this direction, RTPengine will inject the rtcp-mux
> parameter, and this reINVITE is forwarded to the UAC that sent the
> original INVITE.
>
> However, the SDP in the reINVITE is exactly the same as the SDP in the
> 200 OK to the original INVITE, with the exception of the rtcp-mux
> parameter. Since the SDP offered from the same end has changed,
> shouldn't session version be incremented as well?
>
> Does this sound like something that should be reported as a bug to
> rtpengine? Or am I missing something here?

Technically of course you're correct in that the version counter should
be incremented if the SDP changed. Currently rtpengine always leaves the
o= line unchanged, so there can be a discrepancy here in certain cases.
This should probably be fixed, but this is also the first time I've
heard of this actually causing an issue.

Cheers

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