USA Country Code: What +1 Covers and How It Works

The country code for the USA is +1 — but +1 is not exclusively American. It is the code of the North American Numbering Plan (NANP), a single numbering zone that spans the United States and its territories, Canada, and some eighteen Caribbean and Atlantic nations and territories — about twenty countries in all. Dial +1 and you have selected the zone; the three digits after it select the country.

That zone structure explains almost every question people ask about the US country code: why a Jamaican number starts with +1, why some “+1 calls” bill internationally, and why the rest of the world dials Americans with one digit while Americans dial the rest of the world with 011. Our country code guide covers the global system; this page covers the zone the US lives in.

One code, about twenty countries

Most country codes belong to one country. +1 belongs to a plan. The NANP was designed in 1947 by AT&T and Bell Laboratories so long-distance calls could be dialed directly, and it unified numbering across North America before “country code” was a concept most callers would ever meet. Today the plan is managed by a neutral administrator under FCC oversight.

The +1 zone includes:

• The United States and its territories — Puerto Rico, the US Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands all have +1 area codes.
• Canada — same code, same format, its own area codes.
• Bermuda and much of the Caribbean — the Bahamas (242), Barbados (246), Jamaica (876, 658), the Dominican Republic (809, 829, 849), Trinidad and Tobago (868), and more.

Inside the zone, national identity moved down a level: the area code, not the country code, tells you which member you reached.

Inside a +1 number: zone, area code, prefix, line

A full US number in international form is +1, then ten digits: a 3-digit area code, a 3-digit prefix, and a 4-digit line number — +1 212 555 0123, written for machines as +12125550123. Each layer narrows the target: +1 selects the NANP zone, the area code selects a numbering region within it, and the prefix selects a carrier block inside that region.

The layers below +1 have their own guides. What an area code is and how regions get them is covered in our area code explainer; how the prefix and line number work is in the NPA-NXX breakdown. The machine-readable +1XXXXXXXXXX form — and the 15-digit ceiling every international number lives under — is the E.164 format standard, which is what SIP trunks and carrier routing engines actually parse.

Calling a US number from abroad

From outside the +1 zone, the recipe is always the same three pieces:

Your country’s exit code + 1 + the ten-digit US number.

From most of Europe the exit code is 00, so a caller in London dials 00 1 212 555 0123. On any mobile phone worldwide, the + symbol substitutes for the local exit code — +1 212 555 0123 works from every country, which is why numbers shared internationally should always be written with the +.

Note what is not in the recipe: no trunk prefix to drop. Unlike numbers in the UK or Germany, US numbers have no leading 0 that domestic callers use and international callers remove. The ten digits are the ten digits from everywhere.

Calling out of the US: the 011 exit code

Going the other direction, 011 is the NANP’s exit code — the string that tells a US switch the digits that follow are international. The pattern is 011 + country code + national number, and on mobiles the + substitutes for 011 just as it substitutes for 00 in Europe.

What changes from destination to destination is the national number itself — many countries have a trunk prefix that gets dropped and number lengths that vary by region. Those rules are per-country; our country code list links dialing guides for the major destinations.

When +1 is not domestic: the Caribbean billing trap

Here is the sharp edge of the zone: a call to a Caribbean +1 number dials like a domestic call — no 011, no obvious warning — but it is an international call to another country, and it can bill accordingly. Nothing about 809 or 876 on a screen says “this is not the US.”

Scammers have leaned on that gap for decades. The FCC has repeatedly warned about “one-ring” callback schemes: a missed call from an unfamiliar +1 Caribbean number baits a return call, which quietly connects to an international or premium-rate destination. The screening rule mirrors the one for spoofed caller ID: do not return calls to numbers you do not recognize, and if the caller claims to be a business, look its number up yourself. For outbound operations, dial plans should treat non-US +1 area codes as the international routes they are.

Getting US numbers inside the +1 zone

For businesses, +1 is inventory. SIPNEX is an FCC-licensed carrier holding US number stock directly: local DID numbers across US area codes and rate centers, and toll-free numbers issued under our own RespOrg authority rather than rented through an intermediary. Numbers are provisioned by rate center, delivered over SIP, and signed at A-level attestation under our own STIR/SHAKEN certificate.

If your traffic leaves the zone, we keep the economics honest rather than impressive: no thousand-line deck, just prices on the handful of routes you actually run — ask.

Frequently asked questions

As a direct FCC licensee, 499 filer, and registered RespOrg, SIPNEX holds its own number inventory — local DID numbers across US area codes, toll-free numbers, dialer-grade SIP trunking — and signs outbound traffic with a STIR/SHAKEN certificate it holds itself. Call us at (833) 665-2220 or reach an operator.