[asterisk-dev] Asterisk 16 / pjsip: actual SDP handling in case of late offer during outbound call seems to break call

[Joshua C. Colp]

On Mon, Jun 17, 2019, at 3:10 PM, Michael Maier wrote:
> Hello!
> 
> I'm facing a problem on an outbound call which receives a reInvite w/o 
> SDP (late / delayed offer technique) from ISP. The ISP won't provide
> any SDP in the following received ACK and the call is broken therefore 
> afterwards because no more media is sent after this reInvite.
> 
> 
> Detail:
> 
> - ISP sends ReInvite w/o SDP
> - Asterisk sends 200 OK containing the SDP, received by the initial 200 
> OK from the ISP before
>   (which is a subset of the defined allowed media for this trunk).
>   The <sess-version> in the SDP of the 200 OK as answer to the reInvite 
> is the same as the one of
>   the initial INVITE though the SDP is different. Shouldn't 
> <sess-version> be increased if SDP
>   is changed changed?
> - ISP sends an ACK - but w/o SDP -> Call is dead from now on.

Yes, if the SDP is changed then the session version should be incremented. If this is not done then this is likely a bug in pjmedia-sdp (I don't believe we deal with the session version, it's down in the PJSIP SDP side). You can file an issue[1] with the details.

[1] https://issues.asterisk.org/jira

-- 
Joshua C. Colp
Digium - A Sangoma Company | Senior Software Developer
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