Given internal directory number, how do you find the External Number that directs to it?

Question

Given an internal directory number, how do you find the External Number that Cisco call manager would direct to it?

We have a large spreadsheet of available numbers with associated Externals Masks beside it, but a portion are wrong. I'm looking for a way to get external mask from the call manager without relying on the spreadsheet of numbers. It would then be added to the External Mask Field when creating a DN for that number.

Looking through route plan report, I can search through translation patterns for the external numbers, but cannot search by the new translation/internal numbers. This makes finding the internal given external feasible, but not the other way around.

As a followup question, is there some way search for translation patterns that match a given number, or to check what the final internal number of an external incoming call would be without test calling it?