I have a paging system connected to an FXO port on a 2821 ISR. Users complained today that they get busy when they dial the paging number. There have been no config changes. This was working yesterday. Resetting the port did not resolve the issue. They are doing construction at this site - I suspect the line has been cut. Is there a way I can tell if there is nothing connected to the FXO port without being at the site (ie remotely)?