Lync.geek.nz: Lync 2010 and Lync for Mac 2011 Dont Play With Exchange Unified Contact Store

When the Microsoft Exchange 2013 Unified Contact Store is deployed for Lync Server 2013, and its is enabled for a user, the Lync 2010 and Lync for Mac 2011 clients do not understand where to update or save changes. As a result, users who are enabled for the Unified Contact Store cannot change their contacts list from Lync 2010 and Lync for Mac 2011.

http://support.microsoft.com/kb/2757458