|456||International inbound 56K data (for ISDN use)|
|500||Personal Communications Services ("follow-me" numbers)|
|(522)||Personal Communications Services (implementation not yet scheduled)|
|533||Personal Communications Services|
|544||Personal Communications Services|
|566||Personal Communications Services|
|(577)||Personal Communications Services (beginning 2014–Q2)|
|(588)||Personal Communications Services (implementation not yet scheduled)|
|600||Canadian services, including caller-pays cellular (within Canada only)|
|700||Carrier-specific services (generally not toll-free)|
|710||U.S. Federal Government (authorized users only)|
|(822)||future toll-free (implementation not yet scheduled)|
|(833)||future toll-free (implementation not yet scheduled)|
|880||Paid international calls to +1 800 (discontinued)|
|881||Paid international calls to +1 888 (discontinued)|
|882||Paid international calls to +1 877 (discontinued)|
Toll-free services are essentially automated collect calls. The recipient of the call pays the cost. However, many toll-free numbers only work within a limited subset of the North American Numbering Plan countries (for example, only the U.S.A., or only the U.S. and Canada), so "replace" codes were implemented for the first three toll-free codes: 800, 888, and 877. To dial a U.S.‑only 877 number from another NANP country, a caller might dial 1‑882‑nxx‑xxxx. The caller paid the same international call charge as for a standard call to the United States. These codes could also be used for calls originating outside the NANP. However, the use of the 880/881/882 codes was discontinued as of 2004‑04‑01.
International inbound 56K data calls require a special code because normal international calls may be routed to any North American carrier at the convenience of the originating country's telco. A randomly selected carrier in North America may not provide appropriate facilities for terminating a high-speed data link. Thus, calls to the 456 area code are routed to a specific carrier based on the number dialed. This code is not used for domestic calls, but could in theory be used for international calls within the NANP.
Information services provide some form of content for a charge over and above the cost of the telephone connection itself. Many information services provide sexually explicit adult content, but there are other uses, such as per-incident telephone technical support for computer software, automated donations to charitable organizations, psychic / astrological / Tarot readings, stock quotes, and allegedly lucky lottery numbers.
Carrier-specific numbers may be used for almost any purpose a long-distance carrier may devise. There were some carriers in some areas of the U.S. who used 700 as a replace code for the caller's own area code, in order to route intra-LATA toll calls on the long-distance carrier instead of the local "Baby Bell"; however, that practice is discouraged, since it is now possible to presubscribe intra-LATA toll calls to your long-distance carrier. Some carriers use some 700 numbers for information services at charges comparable to 900 numbers. Other carriers use 700 numbers for purposes carrying more modest price tags. Almost all carriers use 1‑700‑555‑4141 to verify the caller's default long-distance carrier for inter-LATA calls. Many areas use 1‑NPA‑700‑4141 to verify the intra-LATA toll carrier, where "NPA" is the caller's own area code; however, you should check with your telephone company, since 700‑4141 may also be an ordinary number in your area code.
Personal Communications Services (a.k.a. "the Other PCS") in this context refers not to cellular telephones, but rather to so-called "follow-me" numbers. The idea was to have a single number, say (500) 123‑4567, that you could program to ring your home phone from 6 to 10 p.m., go directly to voicemail at night, and ring your desk at work during the day. The number could also have some sort of response menu, along the lines of "press 1 for voicemail, 2 for fax, 3 for cellphone." Some implementations also allowed the same 500 number to be used for caller-pays or called-party-pays: dialing 1‑500‑xxx‑xxxx, the caller would pay the cost of the call, but dialing 0‑500‑xxx‑xxxx, the caller could enter a 4-digit PIN to charge the call to the owner of the number. However, in spite of some attempts to keep telesleaze out of the 500 number space, some unscrupulous operators exploited a feature that allowed 500 numbers to forward internationally, with the additional charge borne by the caller with only a "press 1 to accept" warning, if that.
The 533, 544, and 566 codes were assigned as an expansion of 500, although no one is quite sure why they were assigned, since demand for 500 numbers has been steadily decreasing. The assignment of 533 was withdrawn, but later reinstated. As of 2008‑05‑23, NANPA projected activating 533 in the second half of 2009; however, 533 has been "within 6 to 18 months" for several years now. In particular, as of 2008‑01‑01, there were 79 available (500) prefixes to be assigned. In the first 5 months of 2008, 43 of those were handed out; however, 171 other (500) prefixes were returned or reclaimed, leaving 207 available for assignment. That's not a very intimidating demand curve from where I sit. Apparently, somebody is using this number space, though, because NANPA says they ran out of (500) prefixes, and 533, 544 and 566 are now active, with 577 expected in the second quarter of 2014. Once those run out (in reality or in fantasyland), the remaining 5YY codes will be assigned, 588 and 522, but not 555 or 599. After that, the remaining 52x codes and a smattering of other random 5xx codes will be assigned.
The 600 code is used for certain services exclusively in Canada. One purpose for which 600 numbers are used is caller-pays cellular. L'indicatif 600 s'utilise pour certains services non-géographiques exclusivement au Canada, y compris le service cellulaire avec paiement par l'appelant.
The 710 code is used by the U.S. Federal Government for official emergency purposes. Very little specific information is publicly available.
The original toll-free 800 code has been expanded to 888, 877, 866, 855, and now 844 (as of 2013‑12‑07). The next codes added will be 833 and then 822. After that, the remaining 88X codes will be used.
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Last updated 2013-12-07.
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