I upgraded call manager from 5.1(2) to 6.1(2). I upgraded attendant console for the reception. Most of the features are working.
When the call come in attendant console does not see an incoming call under CALL PROCESSING window.
If you do not configure the user, the attendant console cannot interact with CTIManager, and the attendant cannot receive calls so configure the user.
Cisco CallManager Attendant Console Frequently Asked Questions.
Cisco CallManager Attendant Console Issues