How Ring Who works

North American phone numbers have three parts: a three-digit area code, a three-digit prefix (also called the exchange or central office code) and a four-digit line number. The first six digits tell you a lot.

What we show

Area code. Which state or province, which overlay codes share the area, and the local time there. From the NANPA area code database.

Prefix. The U.S. central office code records list every assigned prefix with the company it was assigned to and the rate center, which is the local calling area. We turn those into a place name and a carrier, and we group carriers by type: mobile, local phone, or internet and business phone.

Official numbers. A short list of well-known company and agency numbers, each checked against the organization's own website.

What we can't show

Who owns a number. Names aren't in the public numbering data. Sites that claim to show them use paid data brokers, and the results are often wrong or years out of date. We'd rather tell you less and be right.

Where a caller is right now. People keep their numbers when they move, and a number can ring on any phone anywhere, so a prefix shows only where it began.

The carrier today. People can move numbers between carriers, and most prefixes are shared in blocks of 1,000 numbers. We show the company that held the prefix; the line may now be elsewhere.

Canadian prefixes. Canada's administrator doesn't publish them, so Canadian numbers get area-level answers.

The caution rating

We flag things that are facts about the number: an area code outside the U.S. and Canada that looks domestic, a prefix that isn't assigned to any company (so a real phone can't have that number), premium-rate codes, and numbers that belong to internet phone carriers, which both real businesses and robocallers use. A "looks ordinary" result doesn't mean a caller is honest, and a caution flag doesn't mean they're not. Treat it as one clue.

Privacy

The lookup runs in your browser. The number you type isn't sent to us: the page downloads the data for the area code and checks it on your device.

Sources

• NANPA central office code assignment records (U.S. and territories, updated 2026-10-10)
• NANPA area code database (updated 10/06/2026)
• Wikipedia list of area codes, place descriptions under CC BY-SA 4.0
• Official numbers: each company's own website, linked on its page