Area code lookup

What an area code actually is

An area code — a Numbering Plan Area, or NPA, in the industry’s own language — is the first three digits of a North American phone number, and it identifies a region rather than a town. Some cover a single dense borough; others cover most of a state.

When a region runs short of numbers there are two fixes. A split carves off part of the territory and gives it a new code, which forces everyone in that part to change their number. An overlay layers a second code over the same ground, so existing numbers are untouched and only new lines get the new code. Overlays have been the standard answer since 1992, which is why most large metros now have three or four codes covering identical streets.

That is also why an overlay code is not “less local” than the original. It covers the same place. The only difference is when it arrived — though in a handful of cities, that difference has become a signal in itself.