Your network contains a Microsoft Exchange Server 2010 organization. You deploy Lync Server 2010 on the network. You need to ensure that you can enable Unified Messaging (UM) for all Microsoft Lync 2010 users. What should you add to the network before you enable UM?

A.
a Director

B.
an Enterprise Voice route

C.
an Enterprise Voice dial plan

D.
a Mediation Server

Explanation:
The best I could find on this (http://blog.schertz.name/2010/11/lync-and-exchange-um-integration/)