I'm working on an older Panasonic system, KX-TD816 with a KX-TVS50 VM installed on it. We went to troubleshoot a voicemail issue the other day, and found that only one of the ports was answering. We suspect that either the port was somehow disabled, or that the VM might have a bad port.

Searched high and low through the manual for a way to find out if the ports disabled, and a way to enable it if it is. Anyone have any suggestions?