We upgraded our CUCM from version 6 to 7.1.3 and have come across a number of issues with analog phones and faxes unregistering from call manager and requiring voice-port shut-no shuts to register properly. We're trying to narrow the problem down and ensured that the sccp identifiers on the MGCP VG224's and 3845's are now pointed to version 7.0. However, we're receiving the "Device Is Not Trusted" warning on these gateways in CUCM as well as the analog phones connected to them. Is there a way of debugging why a gateway is not trusted and would this problem cause analog phones to unregister with CUCM (seeminly at random)? Perhaps this is a bug that has been fixed in a later version of CUCM?