You can open a TAC case and collect some details debugs, if you have a contract.
You can also try changing ports (and the configuration for the related port) to see if it happens on another port.
May also want to check deeper into your network to see if anything else has changed.
For instance, upgrading from CUCM 6 to CUCM 7 would change your phone loads, and the phone load in CUCM 7 by default has a nasty duplicate DTMF bug. This duplicate DTMF bug may be causing users to dial the wrong number when they dial in. (If your IP phones are 8.4.1 or 8.4.1 sr 1 this is the problem).
You can check show diag to make sure the board is 'analyzed' and doesn't have an error message related to it.
But there is no 'check hardware' command or anything like that.