Couple of things.
1) if you change the userID for something else in AD, you'll lose ALL your users.
2) You can't create any random field they like and use it as userID, we only provide some options for it
LDAP Attribute for User ID | If synchronization with the LDAP server is enabled, you can choose an LDAP attribute value for the user ID. Choose one of the following values from the drop-down list box: •For Microsoft Active Directory –sAMAccountName –mail –employeeNumber –telephoneNumber –userPrincipalName |
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_1_2/ccmcfg/b02ldsys.html
If they still want to do this they'll need to use one of the above fields and be willing to lose the current users configuration as they will be deleted.
You'll need to delete the whole LDAP integration and recreate it to use another userID.
HTH
java
If this helps, please rate
www.cisco.com/go/pdihelpdesk
HTH
java
if this helps, please rate