How to Format 10-Digit Phone Numbers
ENDORSED: Daring Fireball: How to Format 10-Digit Phone Numbers
Apple’s Contacts app ... will go so far as to reformat numbers entered in 123-555-1234 format as (123) 555-1234. Apple should update the formatting to go the other way, and turn phone numbers with the area code in parentheses into the 123-555-1234 format. Area codes are no longer optional, which is why they used to be put in parentheses.