I have done integration of VCS (7.2) and CUCM (version 9.1). Call from VCS to CUCM are working but the incoming CLI displayed on CUCM endpoint is "Unknown". Missed call shows the called party's System Name (which is AlphaNumeric).
I found following link which mentions that CUCM has limitation of displaying Alphanumeric CLI for incoming calls.
Since, the above answer was about 9 months ago, Has anything changed in CUCM 9.1 to display Alphanumeric CLI?