Second "100 Trying" after a period

I am using asterisk 13 with chan_sip. I receive calls from an provider and I forward them to my internal infrastructure. From time to time there is a huge delay til the internal phone is found and respond with ringing (10-15 seconds). So when I receive the initial INVITE from my operator the asterisk is responding with 100 Trying. But if there is no other message for 7 seconds my provider sends CANCEL and drops the call. Is it possible to configure chan_sip to re-send Trying after 5 seconds or so?

Where is the delay? If you have control, you should call Progress(), or Ringing().

I think Progress has the side effect that early media is used for ringing, but I’m not sure about that.

Currently for workaround I am using Progress but it generates fake ringing which I don’t want.

By fake ringing, do you mean that ring back is sent as early media, rather than as 180 Ringing? In that case the only option to use Ringing(), but this can result in anomalies like ring back followed by number unobtainable.

The correct method, in SIP, is to send Progress, not Trying. It is just that Asterisk assumes that Progress is always associated with a transition to early media. I have a suspicion that that is because ISDN works that way, and Asterisk is an ISDN system with SIP bolted on, in terms of how it was developed.

I don’t believe there is any way in either chan_sip or chan_pjsip to do that, as well have you confirmed that would actually resolve the issue by contacting the provider and seeking clarification? They may actually want to see 183 or 180 in the first place.

Yes, that’s what I mean.
I don’t want to use Ringing() because it can be followed by number unobtainable or smth like this.

I have already contacted the provider and I hope he will extend the timer on his side.

I just thought there is a way to re-send “Trying” after some period because I’ve seen this option in (if I am not wrong) Genband SBC.

Anyway, thanks for your help! Will try to solve the issue with the provider.


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