Volume = Number of phone calls on a DN over a given amount of time.
Let me clarify my original question....
We have over 700 employees across 50 locations and 1000's of numbers in dozens of DID blocks and single number entries. An RP takes far too long to pick through. On top of that, a DN attached to a device - or even not attached - doesn't mean it's unused. Call volume on DN's is a better indicator on whether or not a DN is being used.
This type of management is old-school telecom, but it works very well. You don't want to waste your DID's, or soon you run out of them - and I'm very close to running out of them. To put it in terms of network administration, you wouldn't waste internal IP addresses by using class-full routing within your network - hence the value of subnetting.
And - I don't want to do this search on a number-by-number basis, I want to search volume on a DN range. I don't see RP's or Unified Servicability reports that can pull off that stunt.....but then again I'm green when it comes to Cisco administration. For now, I want to think it's my own inexperience that is the hindrance.