Searching out there I came across the following thread: https://www.3cx.com/community/threads/sip-trunk-going-over-non-5060-port.48546/#post-196531 This is very similar to an issue I have just encountered and was hoping there would be a resolution/solution without reinstalling the PBX. Just a few moments ago (around 1/2 hour or so) the PBX decided to listen on port 2187 rather than 5060 which is where it normally listens. This caused the phone/extensions to not receive audio and/or connect to outside numbers. Restarting the server resolved this, for now. The system is a Windows Server 2012R2 VM running on ESXi 6.0u2. This (currently) is the only other VM on the ESXi host where the only other item running on it is another low usage VM. I was present when the port decided to listen elsewhere and not continue to listen on port 5060. Testing the firewall prior to this resulted in a clean run. Afterword it showed the listening port changed from 5060 to 2187. Nothing on the system was changed apart from modifying the CDR for a specific type of output. Everything was working just fine until the change. Was there any resolution to the above linked thread? Is there something specific I would need to look into in order to keep this from happening again? I'd rather not schedule a system restart weekly in order to keep this from happening again so any information would be greatly appreciated. Thank you for your time.