Unified Contact Store

The second feature enabled via server-to-server authentication is the Unified Contact Store (UCS), an option that nearly made it into Lync Server 2010, but was scrapped at the very end. Without UCS users maintain separate contact lists within Exchange and Lync, where information might not be in sync, and the data is stored independently. When the UCS feature is enabled for a user, the contact list is consolidated to Exchange and can no longer be directly edited with Lync, but users can now edit their contact lists without being signed in to a Lync endpoint.

The Lync servers maintain a cached, read-only copy of the contact list that users can still view when Exchange is offline, but any modifications are made to the copy that Exchange holds. When UCS is enabled, users see the same people card and favorites lists for contacts. The contacts are de-duped, and support for high-resolution Active Directory photos up to a 648×648 resolution is enabled.

Some of the drivers for this change were the fact that multiple contacts for the same user were returned in many Lync searches, potentially with different data, which often confused end users. Mobile clients also did not always have the same contact information stored locally, so this allows mobile users to see consistent data for a contact.