I had the same issue with not enough information out of the gate. I just created a custom alert. I went to Performance then selected the server the gateway was register to and navigated to Cisco MGCP Gateways -> PRISpansInService. After you get the graph up you can create your own custom alert with custom text that has better speciffics.
Obviously this could be a little different if you're running SIP or H323 and not a PRI.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...