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black - new area code is already in use
blue - mandatory 10D (or 1+10D) dialing is in effect in preparation for an overlay
green - new area code not yet in use
red - special notations
t.b.a. - to be announced • à communiquer • se anunciará
t.b.d. - to be determined • à déterminer • se determinará
‡ - area affected by “The Big 10D”; mandatory 10D begins no earlier than 2021-10-24, no later than 2022-07-15, generally at each carrier’s discretion except where a different date is listed here
$ - test number known to bill

“10D/1+10D” refers to the date on which it becomes mandatory to dial all local calls with the area code. In some areas, you must dial only the area code and number, for a total of 10 digits. In other areas, you must dial 1 plus the area code and number on all calls. In yet other areas, you may optionally dial 10D or 1+10D on some or all local calls, or for calls within your own area code overlay whether the call is local or toll. If no date is listed in this column, the area already has mandatory 10D/1+10D local calls, or the listing is for a non-geographic code (such as toll-free numbers) in which there are no local calls, as such.

“Overlay” refers to the date on which the new code goes into effect; that is, the first date on which numbers in the new code may be assigned and used.

New area codes indicated with a question mark are speculation, based on available industry data. However, the information should not be considered reliable until it is officially confirmed by NANPA.

The Test Number is a special number (usually, though not always, not charged) that allows you to test whether all the links in the chain from you to a new area code are operating correctly. In order for you to reach a new area code, your premises equipment (office PBX, for example) must allow you to dial it. Then the telco central office must accept the new area code as valid and route it correctly. If the new area code is outside your LATA, your chosen long-distance carrier must also route the call correctly. Calling one of these numbers will usually reach a simple recording saying something like, “You have successfully completed a call to area code XXX.” Note that some test numbers are billable numbers, possibly at international rates. However, most test numbers in the U.S. will not bill. In cases where a test number is shown ending with –TEST, dial –8378 (no charge); for –BILL, dial –2455 (billed).

Note that the test number for a new area code is usually disconnected within a few months after the mandatory date. If you dial one of the older test numbers shown here, you may reach an ordinary subscriber.

In early 2021, several area codes that were not expected to run out of numbers until 2024 or later, found themselves with revised projections indicating they need overlays Real Soon Now. The most stark of these is Illinois’ area code 708 (see below).

The state of Illinois approved overlays for area codes 217, 708, and 618, but left the implementation dates open, to be triggered when each area code runs low enough on available numbers. The 217/447 overlay happened on 2021-03-27, 708/464 has finally been scheduled for (2022-01-21), and 618/730 is currently projected for 2026. The plan indicated that there would be a 13‑month transition period in each area for permissive and then mandatory 10‑digit dialing, test numbers, and finally assignment and activation of numbers in the new area code. However, the official announcement of dates for 708/464 came with barely 6 months to the activation date. The saving grace is that 708 and 618 (and all the area codes in Illinois) are slated for mandatory 10D local calls as of 2021-10-24, so a major hurdle for both telcos and customers will already be cleared when the overlays are ready to be activated. (In fact, nationally, of the area codes that are keeping 7D local calls, the first to see an overlay is likely to be Maine’s 207 around mid-2024.)

The state of Missouri approved overlays for area codes 314 and 816, originally scheduled for 2001, then postponed until 2002, then suspended indefinitely. On 2021-10-28, the effective dates were finally announced for 2022 and 2023. Area code 573 is also expected to need an overlay (probably 235), circa 2024, but details have not yet been officially announced.

The Canadian province of Newfoundland and Labrador was scheduled to have an overlay of new area code 879 on existing area code 709, effective ‎2018-11-24‎, but evolving conditions led the CRTC to postpone the overlay repeatedly, and finally postpone it indefinitely.

fr: La province canadienne de Terre-Neuve-et-Labrador devait mettre en œuvre un recouvrement de l’indicatif 709 avec le nouvel indicatif 879, à compter du ‎2018-11-24‎, mais en raison des conditions évolutives le CRTC a remis plusieurs fois le recouvrement, et enfin le remit indéfiniment.

The Canadian province of New Brunswick was scheduled to have an overlay of new area code 428 on existing area code 506, effective ‎2020-11-21‎, but evolving conditions led the CRTC to postpone the overlay, first to ‎2022-04-23‎, and again to ‎2023-04-29‎.

fr: La province canadienne du Nouveau-Brunswick devait mettre en œuvre un recouvrement de l’indicatif 506 avec le nouvel indicatif 428, à compter du ‎2020-11-21‎, mais en raison des conditions évolutives le CRTC a remis le recouvrement. La date d’entrée en vigueur de ‎2022-04-23‎ a été remis encore jusqu’au ‎2023-04-29‎.

In southern California, two old area code splits have been erased in a maneuver known as a “boundary elimination overlay”. In downtown Los Angeles, the boundary between 213 and 323 has been eliminated; in San Diego, the boundary between 619 and 858 was eliminated. In each case, the two existing area codes became an overlay, with numbers from either code assignable anywhere in the combined geographic territory.

Area code 870, which covers most of the land area of the state of Arkansas, was scheduled to have an overlay on ‎2013-05-18‎, but number conservation measures extended its life by several years, so the overlay has been postponed indefinitely. Look for it some time around 2023. In the mean time, though, area code 870 will retain 7‑digit local calling, because there is no 870‑988 prefix.

There have been no area code splits — only overlays — since ‎2007-10-07‎, and no splits are planned. Canada has not had an area code split since ‎1999-01-25‎; Canada had its first overlay on ‎2001-03-25‎ and hasn’t looked back.

In fact, Canada is already planning overlays in every province, not including the territories of northern Canada, between now and 2024, although the overlay for Newfoundland and Labrador has been postponed indefinitely. When that overlay finally happens, the only parts of Canada Without overlays will be area code 867 (Yukon, Northwest Territories, and Nunavut) and area code 807 (northwestern Ontario, including Thunder Bay). On the chopping block also are local interprovincial 7‑digit dialing arrangements for Labrador City and Wabush, NL, and for Campbellton, NB, into the 418 & 581 & 367 area of eastern Québec. Those 7‑digit dialing arrangements will be terminated when Newfoundland & Labrador and New Brunswick implement mandatory 10‑digit local calls in preparation for their own overlays.

fr: En fait, le Canada prévoit déjà recouvrir tous les indicatifs (sauf 867 et 807) avant 2024, mais le recouvrement de Terre-Neuve-et-Labrador (709) a été remis indéfiniment. À partir de ce recouvrement, les seules régions du Canada sans recouvrements seront l’indicatif 867 — le Yukon, les T.N.O., et le Nunavut — et l’indicatif 807 — le nord-ouest de l’Ontario, y compris Thunder Bay. On va éliminer aussi les arrangements interprovinciaux de composition locale à 7 chiffres pour Labrador City et pour Wabush, et pour Campbellton, Nouveau-Brunswick, vers l’est du Québec. Ces arrangements seront remis lorsque Terre-Neuve-et-Labrador et le Nouveau-Brunswick mettront en œuvre la composition locale obligatoire à 10 chiffres pour se préparer à leurs propres recouvrements.

Don’t see a split listed here that used to be? Splits and overlays that have been cancelled or indefinitely postponed may no longer be shown.

Time Zone information is now available on the “Locator” page, which lists all active and upcoming area codes in numeric order with major cities.

There is an excellent listing of state/provincial regulatory agencies [link updated ‎2017-05-24‎] provided by the state of New York.

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