I’ve had several customers and colleagues asking about reverse number lookup in Lync, but has not been able to figure out how this is supposed to be working until recently.
Came accross this article which set me off in the right direction(at least it’s working).
Lync looks at the following attributes to retrieve phone numbers:
“LineURI” (Lync Management Shell) / “URI” contact attribute
Telephone number attributes in Active Directory
This means, the contact has to be defined as a mail contact on the Exchange server(with phone number in full E164 format), which in turn syncronizes the information with Active Directory and Lync.
Lync doesn’t look directly into AD, but maintains its own copy of the AD attributes in the Offline Address Book. Make sure you force a sync first if you’d like to have up to date information.
Universal Communications, My experiences. 