I tried to set up CUCM V7.1.3 with LDAP Auth. I configured the CUCM to use UPN as username. I used [email protected] in LDAP Manager Distinguished Name in LDAP Directory and the LDAP user Search base is dc=netlab,dc=loc. It works fine. However, when I set up LDAP Auth and try to use the same name [email protected] in LDAP manager Distinguished Name, it fail. I tried different names and change the LDAP port to 3268 base on some Cisco documentation. Nothing works.
Well, that was my next suggestion - sounds like you got that figured out. SamAccountName it is, right?
Have you delegated authority for that account to Read All Attributes on the user objects of the search base OU (and children)? The UPN attribute may not be accessible to the average LDAP query.