If a DID number is mapped to a user in Direct Inward Dialing service, it should show up there. There's multiple ways to handle DID numbers though, depending on the type of trunks. An older method is to just accept the digits from the carrier and perhaps absorb extra or insert any required leading digits to map a DID to an extension; in this case there's no record in the system that shows what DID is mapped to what user.
