In an IP telephony system, some user names do not appear in the corporate directory. This is the case no matter how the system is searched: by first name, last name or extension number. These names are display names, and when the display name for a phone is changed, the new name does not appear in the corporate directory.
The phone's corporate directory application reads the data from the DC directory. No correlation is found between the DC directory and the display names on the phone. To update the corporate directory, create and modify the users through the Cisco CallManager Administration pages.