Area Code Overlay

Rate this page:

Thanks for rating this page!

We are always striving to improve our documentation quality, and your feedback is valuable to us. How could this documentation serve you better?

An Area Code Overlay is an area code that covers the same area as another area code. In North America, each area code has a potential capacity of around 8 Million unique phone numbers (7,919,900 to be exact). Many area codes have exhausted all possible phone numbers, so one or more area codes are added to accommodate.

Area Code Overlays: An Example

212 is the original area code for New York City (Manhattan to be exact). The overlays 646, 917, and 332 have been added as the need for additional numbers has grown. You can see a full list of overlays in the North American Numbering Plan.

Twilio Local Phone Numbers

To check if Twilio has available phone numbers in your primary target area code or an overlay, you should check through the console.

Voice and SMS Capable Phone Number

In the above image, you can see a search for the area code '209', for the general area around Stockton, CA. If you were searching for a San Francisco number, you could try '415' or the area code overlay '628'. Availability will be detailed through results, but Twilio very often will have numbers available from primary area codes and overlays.