Sometime you may change your Mitel desk phone number to something different. In that case, the Mitel’s Unified Communicator Advanced software on your desktop may still point to the old phone number. Here’s how you can change the phone number.
You will need to re-run the configuration settings. Delete the uc.cfg file found in the c:\Documents and Settings\USERS\Application Data\Mitel\UC
Uc.cfg contains all persistent settings of the application, including configuration settings and GUI layout settings. Deleting this file resets the Desktop Client to default settings.