you need to establish how the call is cleared. It might be a disconnect tone sent from the carrier. To prove this place a call into an ip phone from outside on the fxo port hang up the calling phone but keep the ip phone off hook, if you hear a tone after a few seconds then that is most likely the disconnect tone. what may be happening is that the tone is not always recognised by the cisco router. If you never hear a tone then you will need to look at other disconnect issues. But let us know how you get on.
the simplest way in my opinion to check to see if the FXO port or signaling is an issue is place a call from the pstn and then hang up. check to see if the ip phone still rings. if going to an AA do a show voice port summary and see if the FXO is still off hook.
if thats the case then you will have to do some tweaking to resolve disconnect issue.
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...