Travis, Great idea. Is there a slight change that this might match a contact where the three digit strings for area code, prefix and last-4 are matched but are in a different order in the phone number?
In which case the query would return more than one item. So maybe add in some logic to test for > 1 item returned and then test the items returned to find the one where the components of the phone number are in order from left to right.
One other thought is to do a clean-up of your phone number formatting by exporting contract/accounts from AT, reformatting them with Excel and using import-with-update so all stored phone numbers conform to your “standard” format. This helps a lot but does not keep new entries in your standard format.
I do wish AT supported phone number formation rules.