When an attempt is made to access the fast dial feature, the IP Phone displays the Personal Fast Dials: Error: -7ffbc50d:user (xxxx) was unable to be validated.(15091) error, and it is not possible to see or dial the fast dial numbers from the personal address book.
In order to resolve this issue, complete these steps:
In enterprise parameters, verify that the phone URL parameters are set to the IP address and not to the hostname.
Open Internet Services Manager from administrative tools in Cisco CallManager.
Under Default Web Site, expand the parent directory, and choose the CCMUser virtual directory.
Under Anonymous Access and Authentication Control, right-click the virtual directory, and choose Properties > Directory Security > Edit.
Under Anonymous Access, choose Edit. The user ID displays Username in the text box.
Give this user ID write permissions on the C:\dcdsrvr\log folder and all the files and subfolders under it.
Re-start the Internet Information Server (IIS) admin service on Cisco CallManager.
Re-boot the phone and check if fast dials work properly.
If the issue is still unresolved, reconfigure the DC Directory. There are two possible scenarios to reconfigure the DC Directory after installation. Refer to the Reconfigurationsection of Fixing Problems with DC Directory for detailed steps on how to reconfigure the DC Directory.