@SummerinGreece Yes, phone numbers are always a headache. 😑 I have used the Modify module in DemandTools in the past to add country codes and format numbers in desired formats for different regions. It was beast to set up, but the upkeep after that wasn't bad. Do you have any tips and tricks as to what you've done to standardize phone numbers?
My favorite data clean up jobs were always trying to find and replace the weird values people would put in the first name field as a place holder. Hi Mr. "Don't Know Yet" hoping you are loving our product. 😬 It was always a fun game of trick the system trying to query the different values in either Modify or Tune to track down the culprits.