Similar to Call Park, the Unassigned Numbers feature was first introduced in Lync Server 2010 and will be a welcome addition for organizations migrating from Office Communications Server 2007 R2. The Unassigned Numbers range enables companies to send calls that don’t match a user to an operator or attendant instead of returning a user-not-found message to the caller.
The ranges defined for unassigned numbers can actually contain numbers that are assigned to users. Lync prioritizes a user matching the number over the unassigned number range so that it does not interfere with call routing. A best practice is to include each number range used by an organization.
Calls that match an unassigned number range can be routed ...