[Spce-user] Call forward hangup when having early ACM

[Alex Lutay]

Hi David,

It is a hard to say something from this side without logs,
debug and environment to reproduce the issue.

On the first looks it is a Sems issue. The CE release mr4.5.4
is based on GPL sems 1.6. As the next step I  would recommend
you to fire the latest mr8.5 LTS VM and repeat your tests
there. With a good chance your issue can be addressed there
already. The release mr4.5.4 is 3+ years old.

As the last resort your can contact Sipwise sales@ and repeat
your test with PRO based system, which is based on commercial
Sems 2.3 with a LOT of different fixes we cannot publish due to the
license limitation.

Sure you are always welcome for pull request to GPL sems 1.6:
https://github.com/sipwise/sems

Have a nice day!

On 9/10/20 11:32 AM, David Pareja | Ingeniero de Red - Telmi Telecom wrote:
> Hello,
> 
> I am using SPCE mr4.5.4 and I have the following problem: When receiving
> a call from the PSTN and then performing a call forward to the PSTN
> again, if there is Early ACM involved (RFC 3398 Sec. 7.2.5) in the call
> (and therefore the SPCE reveives an 183 Session Progress from the peer
> before the 200 OK to the INVITE), the SPCE responds with a PRACK and
> after that it doesn't respond to the 200 OK corresponding to the INVITE.
> The call is stablished and RTP starts flowing, but the peer keeps
> sending the 200 OK since we didn't respond with the corresponding ACK,
> and after a while (about 20 seconds) it does timeout and the call drops.
> 
> When the the call is originated from a subscriber (instead of the PSTN)
> the call forward is performed correctly. Looking at the traces it's like
> the SPCE ignores the 183 and just waits until it receives the 200 OK
> corresponding to the INVITE. In this case, it does respond with the
> usual ACK and the call doesn't drop.
> 
> I don't know if there's a known issue regarding this specific aspect of
> the Early ACM with call forwards from and to the PSTN. I already deeply
> searched in the documentation, the internet and the files within the
> SPCE, so I ran out of options. I would greatly appreciate any feedback
> regarding this topic.
> 
> Thank you very much.
> 

-- 
Alex Lutay