The Mediation Server role of Microsoft Office Communications Server 2007 R2 does not forward the Display Name information that is associated with the calling party. This information should be forwarded from the gateway side to the proxy side or from the proxy side to the gateway side for an initial invitation.
To resolve this issue, apply the following update:
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
970679 (http://support.microsoft.com/kb/970679/ ) Description of the update package for Office Communications Server 2007 R2, Unified Communications Managed API 2.0 Core Redist 64-bit: July 2009
Update 970679 introduces functionality for the Mediation Server role of Communications Server 2007 R2 to forward Display Name information that is part of the From header between its gateway side and its proxy side.
To make sure that the mediation server correctly operates together with private branch exchanges (PBXs), update 970679 adds a new Mediation Server configuration file setting for Communications Server 2007 R2. This configuration file setting is called forwardDisplayName, and it contains a value that is true or false.
Note This setting only controls whether the Display Name information is forwarded from the proxy side to the gateway side of the mediation server when this software update is applied. After this software update is applied, the Display Name information is always forwarded from the gateway side of the mediation server to the proxy side of the mediation server regardless of the forwardDisplayName configuration setting.
This configuration file is named “MediationServerSvc.exe.config.” You should put this file in the directory in which the mediation server is installed. To locate this directory, search for the Microsoft.RTC.MediationServerCore.dll file and note the directory in which it appears. Then, put the MediationServerSvc.exe.config file in the same directory.
Note By default, the mediation server is installed in the following directory:
c:\Program Files\Microsoft Office Communications Server 2007\Mediation Server
If the MediationServerSvc.exe.config file is set to forward the Display Name information from the proxy to the gateway side of the mediation server, the MediationServerSvc.exe.config file should have the following contents:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="forwardDisplayName" value="True" />
</appSettings>
</configuration>
If the file does not exist, or if the file exists but does not have the forwardDisplayName setting, the setting is assumed to be false
So let’s look at how this is handled by OCS.
Below is a screenshot of incoming call into OCS, in this case the Callers extension is not in Active Directory
The name is shown in OCS ” LinkDev-Cisco-User “ to show that the Callers Name has come from the PBX in this case a Cisco Call Manager rather than from Active Directory
The final part is an OCS User calling a PBX Phone, this functionality is not enabled by default and requires a changed on the Mediation Servers.
The screenshot below is the Cisco IP Communicator; the Phone Number is not known to the PBX and as such would result in just the Callers Phone Number being displayed prior to the July Update. 
