Best way to approach user regarding phone number formatting?

1. How do you professionally format a phone number?
2. How do you layout phone numbers?

How do you professionally format a phone number?

Since the U.S. and Canada both use the North American Numbering Plan, the commonly accepted formatting of phone numbers is (NPA) NXX-XXXX, NPA-NXX-XXXX or 1-NPA-NXX-XXXX, where 'NPA' is the area code, 'NXX' is the central office code and 'XXXX' is the remaining subscriber number personal to each phone number.

How do you layout phone numbers?

Landline phone numbers begin with the area code, then one digit for the operator code, then six digits for the primary telephone number. Format: (XXX Y ZZZZZZ) where: "xxx" denotes the area code. All area codes begin with the number 0.