Area Codes and the North American Numbering Plan
An area code is the first 3 digits of a 10-digit phone number in the North American Numbering Plan (NANP), the shared numbering system used by the United States, Canada, and about two dozen Caribbean and Pacific territories. The area code identifies a geographic region (like 212 for Manhattan) or a service class (like 833 for toll-free).
A full NANP number looks like +1 (NPA) NXX-XXXX: the country code 1, a 3-digit area code (NPA), a 3-digit exchange (NXX), and a 4-digit line number. Both the area code and exchange must start with digits 2-9.
Country Calling Codes
Outside North America, the first digits after the + are the country calling code, assigned by the ITU: +44 for the UK, +49 for Germany, +91 for India. Codes are 1 to 3 digits, and no code is the prefix of another, which is why a phone can always work out the country from the first digits. See the complete list.
Toll-Free and Special Codes
| Codes | Meaning |
|---|---|
| 800, 833, 844, 855, 866, 877, 888 | Toll-free: the business pays for the call. No geographic location. |
| 900 | Premium rate: the caller pays extra. Historically used for paid services. |
| Most others | Geographic: tied to a state, province, or territory. |
Using Prefixes Against Phone Scams
The prefix is your first defense line against unwanted calls:
- One-ring international calls (Wangiri). A missed call from a code like +252 or +881 that rings once. Calling back connects you to a premium-rate number. If you don't know anyone there, don't return the call.
- Neighbor spoofing. Scammers fake a caller ID with your own area code and exchange so the call looks local. A familiar area code alone is not proof of a genuine local caller.
- Toll-free pressure calls. "Your account is suspended, call this 8XX number." Legitimate organizations don't object to you hanging up and calling the number on their official website instead.
The rule that beats all of them: never share personal or payment information on a call you did not initiate.
Frequently Asked Questions
Why do some US cities have multiple area codes?
When a region runs out of numbers, a new "overlay" code is added to the same territory. Los Angeles, for example, is served by 213, 310, 323, 424 and more.
Does an area code prove where a caller is?
No. Numbers are portable and caller IDs can be spoofed. The area code shows where the number was assigned, which is useful context but not proof.
What is E.164?
The international standard format for phone numbers: + followed by country code and national number, maximum 15 digits, no spaces. Example: +14155552671.