Today when a client asks if they can search for devices in FindIT by extension, the answer I give is in the form of the question, "Do you have phone extensions listed in your interface descriptions?"  In short, the answer is almost always "no," which makes my ultimate answer the same.

 To that end, I think it would be great if we could include the extension data that we capture from the call server/detail records in the FindIT search criteria.  Often times that is the simplest information that a help desk can ask a user in terms of finding where their connection points in the network are, as opposed to the MAC or IP of their phone.