This error would indicate that either you have error during the trunk registration or something is wrong during outbound calls. Do you have any issues with outbound calls?
we are using predictive dialer from cfd and the outbound calls seems to be ok although cuz of the Predictive dialer we are not sure if we are losing some outbound calls due to these errors.
We tried to call our DID 10-15 times and half of them we got a voice message saying that the number is not available due to technical reasons. Maybe these errors correspond to incoming calls?