US Phone Number Format: How Many Digits, How to Write It, and Safe Examples

Ten. Take +1 212 555 0123: the 1 is the country code shared by the US, Canada and 18 other countries and territories; 212 is the area code (here, Manhattan, New York); 555 is the exchange, or central office code; 0123 is the line number. With the country code, that makes 11 digits.

If you count 7 digits, the area code is missing — and many areas now require all 10 digits even for local calls. If you count 12 or more, something extra has slipped in, usually an exit code such as 00 or 011.

Two rules hold for every number: the area code and the exchange never start with 0 or 1, and mobiles and landlines look exactly the same. Unlike in many countries, there is no mobile prefix — cell phones and landlines share the same area codes. Only a carrier lookup can tell you whether a number is a mobile, a landline or a VoIP line.

All of these are the same kind of number. Which style to use depends on who will read it:

• (212) 555-0123 — the classic US style, with the area code in parentheses. 212-555-0123 and 212.555.0123 are common too.
• 514 555-0123 — the style Québec's French-language office (OQLF) recommends: a space after the area code, a hyphen before the last four digits, no parentheses.
• +1 212 555 0123 — the international format, for anyone outside North America: a plus sign, the country code, then the digits in groups. Canada's numbering plan follows the ITU's E.123 notation and writes +1 followed by a space.
• +12125550123 — the E.164 format: a plus sign and at most 15 digits, with no spaces or punctuation. It is what phone systems, SMS services and many sign-up forms store behind the scenes.
• 1-800… — toll-free numbers are often written with the leading 1, the way they are dialed inside North America.

Forms differ, but these rules work almost everywhere:

• If the form has a country selector, pick United States or Canada (+1) and type only the 10 digits: 2125550123.
• If there is a single field that asks for the country code, enter +12125550123 — no spaces, and no 00 or 011.
• Don't add a 0 in front, and don't repeat the 1 if the form already shows +1.
• Spaces, dashes and parentheses are usually accepted; if a form rejects the number, try digits only.

For documentation, a mock-up, a script or a test case, use any area code followed by a number from 555-0100 to 555-0199 — for instance (212) 555-0142. NANPA, which administers North American numbers, reserves that block for fictional and advertising use, so it is never assigned to anyone. Avoid making numbers up: a random 10-digit number could belong to a real person.

Other 555 numbers are not safe: since 2016 most of them can be assigned to real lines, and 555-1212 is still directory assistance. And of course an example number can't receive calls or texts, so it is useless for signing up to a service.

The format gives you the +1 zone and the area code, nothing more. It doesn't show where the person actually is: an area code shows where the number was registered, and internet calling apps let anyone keep a New York number anywhere in the world. Our area code lookup gives the region and time zone, and the carrier lookup the line type — none of our tools reveals who owns a number. And +1 alone doesn't even prove a number is from the US or Canada: 18 other countries and territories use it too.

If you live outside North America and need a +1 number — for clients in the US or Canada, say — you don't need a local SIM card. Business phone apps provide local or toll-free US and Canadian numbers that you use over the internet on your phone or computer, and some are open to people based abroad. You can also search real US and Canadian numbers for sale.

Know the trade-off: these are VoIP numbers, not mobile lines, and some banks and apps don't accept VoIP numbers for verification codes. If you need a number to receive codes from a particular service, check that service's rules first.