I host a number of Freepbx servers in a datacenter, that we own and operate with asymetrical 500/500 fiber. Each customer has their own VM on a physical server running their own instance of Freepbx. I have one such customer experiencing issues with dropped calls. It seems to be isolated to their network, however, I cannot seem to identify what is causing it. I say that because I build one of the extensions on my phone here, at a different network entirely, and the call audio never drops. The call doesn’t drop, but the audio does. It’s random and intermittent. It can happen almost immediately into the call, or several minutes, and everything in between.
The carrier I use is Twilio, and I also use their secure trunking, so I have TLS/SRTP enabled, which I understand makes troubleshooting a little more difficult. Any suggestions on troubleshooting this issue given the circumstances?