US phone number regex

What it does

This pattern recognizes ten-digit US-style numbers while requiring area and exchange codes to begin with 2–9. Parentheses are accepted only as a balanced pair around the area code.

Token-by-token explanation

1. ^

   Starts matching at the beginning of the input.

2. (?:\+1[ .-]?)?

   Optionally accepts the literal +1 country code followed by one optional space, dot, or hyphen.

3. (?:\(([2-9]\d{2})\)|([2-9]\d{2}))

   Accepts a three-digit area code either inside balanced parentheses or without parentheses; its first digit must be 2–9.

4. [ .-]?

   Allows one optional separator after the area code.

5. ([2-9]\d{2})

   Captures the three-digit exchange code and prevents it from beginning with 0 or 1.

6. [ .-]?

   Allows one optional separator before the subscriber number.

7. (\d{4})

   Captures the final four-digit subscriber number.

8. $

   Stops matching at the end of the input.

Test strings