When — and Why — Were Area Codes Invented?

About 97% of Americans own at least one cellphone as of 2024 according to Pew Research. Cell phones wouldn't exist today if it weren't for the inventors of the telephone. It's that invention that led to the North American Numbering Plan, which plays a major part in how area codes were invented. It's a three-digit number essential to making calls today. (Find out how people called someone in "27 Incredible Photos Showing What Life Was Like in the 1930s.")

Before modern phone numbers were implemented in 1951, calls were made using a system of letters and numbers. People picked up their handsets and asked the operator to connect them to a specific city and number. Communities often used party lines to lower costs, which meant multiple households on a street or in a town shared one phone line. Each house was assigned a ring pattern to ensure the correct house answered a call.

As populations boomed, the letter and number system ran out of combinations. In 1947, AT&T established the North American Numbering Plan (NANPA) Every state was assigned at least one three-digit area code to use as the first part of a phone number. People started using these new numbers in 1951.

Due to the NANPA's guidelines, an area code cannot start with 0 or 1. They're always structured to be a numbers ranging from 2 to 9 first and then other digits. City exchanges also never start with 0 or 1.

Smaller states usually have one area code to cover the entire state. When a population is 20,000 or more, an area code may be assigned to cover a specific area or city instead. For example, Los Angeles has two area codes due to the massive population.

In addition to standard area codes, toll-free and pay-per-call exchanges are available three-digit starters to a phone number. Toll-free exchanges (800, 833, 844, 855, 866, 877, and 888) mean the company covers long-distance charges for its customers. The pay-per-call or premium code (900 service) requires the caller to pay a per-minute fee.

For decades, people could dial "0" to reach the operator and ask for information regarding the current time weather, or other general information. This ended in 1994 when 555 became the exchange for reaching information services. That same number was also used as a city code on TV shows and movies.

The 50 states were not the only areas receiving a three-digit area code. All U.S. territories, Canada, Caribbean islands, and Bermuda also have NANPA area codes.

With so many possible area code combinations, some are commonly used to commit scams. One of the most dangerous is the one-ring scam where the scammer hangs up immediately after one ring. They want you to call back because that area code is actually an international number, and you're being charged for the time you spend on hold. According to the FTC, those area codes are:

• 268
• 284
• 473
• 664
• 649
• 767
• 809
• 829
• 849
• 876

In addition to an area code, phone numbers include the three-digit city exchange and the phone owner's identifying number known as a "line." These three parts work together to quickly connect a caller with the correct person. If you have a question before visiting the Empire State Building, the historic building's phone number is (212) 736-3100. That breaks down to 212 for New York State, 736 for the city, and 3100 for the building.

Right now, the possible number combinations ensure plenty of potential phone numbers exist. However, experts are looking at the future. Adding just one number to an area code increases the possible number combinations by billions.  In addition to phone number changes, etiquette regarding phone calls also changed. Learn more by reading "50 Things That Were Considered Polite 50 Years Ago."