since a few days we have massive problems with our Sangoma SBC: From time to time we get timeouts and calls fail, in and out. It happens very often - it works for a few minutes, then we get timeouts for some minutes, then it works again.
With tcpdump I see, that the SBC is sending “Status 100 Trying” but there is no following “Status 200 OK” within time, so the trunk peer sends a CANCEL with reason q.850 (cause 27, destination out of order) after 14 sec and the call is aborted.
After some minutes without any change it works again, “STATUS 200 OK” is sent right after “Status 100 Trying”.
Don’t know what happens here, because I don’t see any packet with “STATUS 200 OK” in wireshark I think it has to be a problem in the SBC itself, not regarding to any possible network issues?