We have two Microsoft Office Communications Server R2 x64 servers ( front end and mediation server ) installed on windows server 2008 R2 x64.
The mediation server is integrated with Cisco call manager 4.2(3) and calls from and to Cisco phones are going very well .
The problem that when call is initiated from OCS communicator to a Cisco IP phone the user display name is not sent from OCS server . I had investigated this
in Microsoft website and I found that this attribute is not sent to any integrated party by default . hence it needs some configuration as described in this article from Microsoft Support Site .
http://support.microsoft.com/kb/972721