Assume that you install the cumulative update for Microsoft Lync Server 2010 that was released in October 2012 in a Lync Server 2010 environment. When a Lync Server 2010 user tries to call another user in a different pool in the environment, the Intercluster routing component does not route the call to the callee’s pool.
The issue occurs because the Intercluster routing component is disabled under certain circumstances. Therefore, cross-pool requests are not routed.
Note The Intercluster routing component is responsible for routing requests to users who are homed in other pools.
To resolve this issue, install the following cumulative update:
2791381 Description of the cumulative update for Lync Server 2010: March 2013
For more information about the Intercluster routing component, go to the following MSDN website: