Seven-digit dialling is nearly over: what 454 area codes say about the numbering plan

This is an analysis of the North American Numbering Plan Administrator's own register — the file it publishes listing every area code, where it is, which overlay complex it belongs to, when it entered service, and whether relief planning is under way. The figures below were computed from the copy dated 19 August 2026, and anyone can reproduce them from the same file.

We went looking for something narrow — whether our own area-code data was correct, which it turned out not entirely to be — and found the register says something more interesting than we expected about how quickly the way North America dials has changed.

How many area codes are there?

Eighty-six of the codes assigned when the plan was first drawn up in 1947 are still in service today, which is a remarkable run for any piece of infrastructure. 212 in New York, 213 in Los Angeles and 312 in Chicago have been continuously in use for seventy-nine years.

Is seven-digit local dialling finished?

Nearly. 384 of the 454 geographic codes — 85% — now require ten digits for a local call. Only 70 still permit seven, and the list is short enough to print in full:

207 216 225 228 229 231 239 242 246 252 260 264 268 269 284 307 308 316 320 325
340 345 386 401 413 432 434 435 441 473 479 502 517 563 580 585 586 606 612 636
641 649 651 661 664 670 684 701 712 721 727 734 758 763 765 767 772 784 828 831
863 868 869 901 913 931 936 956 979 985

The reason is overlays. When a code runs low on numbers, the administrator can split the region — forcing half the people in it to change their number — or lay a second code over the same ground, so nobody changes anything and everybody dials ten digits instead. Splits were abandoned as too disruptive, and the consequence is arithmetic: 71% of all geographic codes now share territory with at least one other.

Why did the 1990s add more codes than the previous forty years?

The 1970s contributed a single surviving code. The 1990s contributed 133. That cliff is the mobile phone, the fax machine and the second line for a modem arriving at once: for forty years a household needed one number, and then within a decade it needed three or four.

What is less expected is the 2020s. Sixty-four codes have entered service since 2020, twelve of them in the last two years — a rate close to the 1990s peak, in an era when nobody is installing a second landline for a modem. Numbers are now consumed by mobile lines, business VoIP, connected devices and the number pools that messaging and calling platforms hold.

Which areas are running out next?

The register flags codes where relief planning is under way — the administrative process that precedes a new overlay. Seven are in progress:

828 is worth noting: it is one of the 70 codes still permitting seven-digit local dialling, and relief planning is the beginning of the end of that. When its overlay arrives, western North Carolina joins the 85%.

Where are the codes concentrated?

At the other end, 32 jurisdictions are served by a single code, including fourteen US states: Maine, Delaware, Wyoming, Rhode Island, Montana, New Hampshire, South Dakota, North Dakota, Vermont, Hawaii, Alaska, and the territories. In those places the area code still means what it originally meant — one code, one place, and a number that identifies where it was issued.

The part that matters if you make business calls

Two consequences follow from all of this, and neither is obvious from the numbering plan itself.

The first is that an area code no longer tells you where anybody is. With 71% of codes overlaid and mobile numbers keeping their code across a move, the code is a record of where a number was issued. Any process that infers a caller's time zone from their area code is wrong for a growing share of contacts — which matters when calling-hour rules are set by where the recipient actually is.

The second is that local presence is a narrower technique than it was. It works by presenting a number in the recipient's own code, on the reasonable theory that a familiar code is answered more often. In a metro with eight overlaid codes, a large share of residents hold a code that is local but unfamiliar — and a newly introduced overlay carries no local association at all until people get used to it. The technique still works; it works on fewer people than it did in 1999.