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
