The display names of federated contacts do not appear in a Lync client after you configure federation in Microsoft Lync Server 2013.
Note This issue occurs if the contacts are added to the contact list.
This issue occurs because the Unified Communication Web API (UCWA) does not call the ContactCard control. This control is required to display the names of federated contacts.
To resolve this issue, install the cumulative update that is described in the following article in the Microsoft Knowledge Base:
2835435 Description of the cumulative update 5.0.8308.420 for Lync Server 2013, Web Components: July 2013
For more information about UCWA events, see the following TechNet website: