I have a 3CX PBX setup with sip trunk which registers OK, but sometimes callers state they can't get through (various errors from "there is a fault" to silence). When I try the line myself, it seems to be fine - it rings and I can answer it. Callers are dialling the right number, because they do get through most of the time.
I'd like to try to do some automated testing - most likely dialling the number and hanging up immediately when the it rings, but not sure what I should be using and how to start to go about it. Google doesn't appear to be turning up any relevant results.
I'm not averse to a bit of scripting or configuration, so I'm looking for recommendations of how to at least start to approach this problem.