I've got a head scratcher. I'm using CUCM version 6.x. A particular 7911 phone is having issues with extension mobility. When nobody is logged in, the phone has a single line with extension 6639. When a user logs into the phone using extension mobility, the phone reports that the login was successful but the DNs associated with the extension mobility device profile do not come down. The phone still displays as 6639 and calls to 6639 ring on the phone. If I look at the phone in CUCM, the login information within the Extension Mobility section indicates that a user is logged into the phone. I've tested several extension mobility device profiles on this phone and they all have this issue. I've logged into other 7911 phones with those same device profiles and everything worked fine. I've compared the phone configurations between this one phone and phones which do work and I cannot find any differences in configuration. I'm really at a loss to explain why this is happnening. Any ideas?