What is National Format

Twilio's Lookup API returns phone numbers in national format, a string containing the phone number formatted according to the most common style in the associated country.

North American Numbers

For example, phone numbers in the United States are defined by the North American Numbering Plan (NANP) as ten-digit numbers consisting of:

A three-digit Numbering Plan Area [local link] (NPA) code, commonly called an area code
A seven-digit local number. The format is usually represented as NXX-NXX-XXXX where N is any digit from 2 through 9 and X is any digit from 0 through 9.

The national format returned by Twilio for NANP numbers is therefore (NXX) NXX-XXXX.