6921 and CUPC

My environment:  UCM 8.5.1.10000-26, CUP 8.5.2.10000-49

Starting from UCM 7.1(5), 6921 is consuming 2 DLUs instead of 3 in the earlier version, and therefore it no longer able to be a primary phone for CUPC.  The CUPC itself consumes 3 DLUs, and the primary phone must >= 3 DLUs in order to qualify as the primary phone.

If you try to assign a 6921 as the CUPC primary phone, you will get the message:

"Update failed.  [10205]  The device must use the same or fewer DLUs as its primary phone"