____________________________________________________________________________________________ | 888 d8888 888 | | 888 d8P888 888 | | 888 d8P 888 888 | | .d8888b 888 d8P 888 .d8888b 888 888 .d88b. 888d888 .d8888b .d88b. 88888b.d88b. | | 88K 888 d88 888 d88P" 888 .88P d8P Y8b 888P" d88P" d88""88b 888 "888 "88b | | "Y8888b. 888 8888888888 888 888888K 88888888 888 888 888 888 888 888 888 | | X88 888 888 Y88b. 888 "88b Y8b. 888 d8b Y88b. Y88..88P 888 888 888 | | 88888P' 888 888 "Y8888P 888 888 "Y8888 888 Y8P "Y8888P "Y88P" 888 888 888 | |____________________________________________________________________________________________| Fear and Loathing in the NANP by Cindy Vaxen ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The NANP (North American Numbering Plan) has quite a few rules as to what exchanges, or "NXXes" as they're referred to by the phone company, can be assigned in a given area code (NPA). These range from somewhat obvious to obscure and not entirely explainable. NPA-N11 is somewhat obvious, for example. 911, 811, 711, 611, 511, 411, 311 and 211 and unassignable within any NPA in the case of both "the subscriber might dial this by accident when trying to use special services" and "the switching equipment needs these to stay reserved for routing/translation purposes". IIRC, all of these are technically proper "exchanges" within the LERG, or the Local Exchange Routing Guide (iConectiv/Telcordia/Bellcore/whatever the fuck you wanna call them at this point's central database of what routes where and what equipment is in use at a facility, etc etc), but don't actually route anywhere in most cases and use XXXXXXXXXX as a CLLI code. 555 is within the "DIR ASST" rate center as it has one valid number within every NPA, that being 1212, which is of course used for directory assistance service. While many just use 411 for such now, 555-1212 should still work in most every case. Since all of the other numbers are invalid/unassignable, the prefix is often used in film/television productions since there's no chance you'll get a subscriber on a number within it, avoiding any mass embarrassment. Actually, about that; 555 is valid all-throughout 800 (though none of the other 8YY codes, strangely enough), and once or twice certain people have slipped up and accidentally put numbers to PrimeTel's network of sex hotlines/various scams in their production. The more you know, I guess? Anyway, 011 and 111 are unassignable, but not in the same way, and for a few different reasons. All of the prefixes referred to so far as called "Oddball Codes" or just "Oddballs" in the LERG, but these are entirely invalid. The first reason being that 0xx/1xx prefixes are forbidden from being assigned to any subscriber. Interestingly enough, they DO actually hold numbers, usually ending in 1211, but they're meant to be exclusively for special routing purposes and telephone company use. Phreakers often used to bluebox to these numbers to access various special services, conference lines, etc; but nowadays the easiest ways to route to them are finding a telephone switch that doesn't block them (not as difficult as you'd assume!) or routing thru the AT&T calling card platform (thx unnamed phriend for getting the ATT folks to set that up!). A good example of this is 208-038-1211, which kicks you to a WiMacTel operator w/ an ANI fail. The other reason that 011 and 111 (more specifically 011 in this case) stand out is that 011 is the international dialing prefix for US citizens. Outside of the more obvious N11 codes and "undialable" 0/1s, the LERG holds atleast 60 or so more oddball codes, so what the hell are they for? Some of them are easy to explain. NPA-976, NPA-950, NPA-959/958 and NPA-700, for example. 976 is a prefix assigned for use in premium-rate telephone services, basically 1-900 numbers before they were assigned their own "area" code. 950 is a feature group B code, essentially for routing through a telco-defined calling card platform or specific long distance carrier. Nowadays we typically use feature group D for this, aka 101-XXXX codes or "dial-arounds" as some people refer to them. 959/958 are similar to 0xx/1xx in that they're reserved for telephone company use, in the US atleast. The AT&T long-distance network, for example, does some fun stuff with them; ie recordings about your call failing due to a mudslide in your area and other fun stuff in that same vain. In Canada, who also uses the NANP though with their own seperate non-NANPA numbering agency, 958 seems to be assignable to whatever the hell. I'm not entirely sure about 959, however. Many people know that 700 as an area code generally contains one number, that being 555-4141 (btw, one of the only other uses of 555); to get a message identifying your current long-distance carrier. Teeeechnically it contains other translations on many switches as a result of a failed "personal toll-free" marketing campaign, but that's for another day. What many people DON'T know is that 700-4141 within a given NPA from a real telephone switch'll identify your LOCAL telephone company! Okay, we just went over four or so more. What are the other over 50 oddballs? The fair majority of these, to be honest probably all of them at this point, are defined for the "advanced intelligent networks" of specific telcos. The concept, which is fairly popular in Canada via their 310 NXX in most NPAs, is that your local telco sets aside a few prefixes in various area codes of their for special services. In most cases this refers to defunct sales offices and other depts of the company itself, in some cases it's used for weird local toll-free calling arrangements. While most of these prefixes are entirely abandoned nowadays, for whatever reason they haven't decided to reallocate the fair majority of them. For the hell of it, here's a complete-ish list of these reserved prefixes. ----------------------------------------------------------------------------------------- |201-260, 201-550, 201-717, 201-900, 201-990, 201-999, 203-471, 203-472, 203-473, 203-474,| |203-475, 203-476, 203-478, 212-910, 219-790, 270-204, 305-991, 315-581, 315-850, 315-910,| |316-954, 317-952, 347-660, 347-910, 352-305, 401-844, 407-991, 412-493, 442-730, 480-260,| |501-341, 501-980, 501-990, 502-404, 502-577, 502-578, 502-970, 512-510, 512-951, 516-936,| |516-955, 518-780, 518-850, 518-910, 518-927, 518-979, 518-985, 518-996, 518-997, 518-998,| |551-990, 585-644, 585-702, 585-890, 585-977, 601-204, 601-220, 606-204, 606-844, 606-970,| |606-990, 606-991, 606-992, 606-993, 606-994, 606-998, 606-999, 607-910, 617-508, 617-978,| |631-222, 631-936, 646-910, 684-631, 684-639, 684-685, 716-850, 716-927, 716-977, 716-996,| |718-660, 718-910, 718-955, 718-985, 802-508, 802-617, 808-360, 808-370, 812-540, 812-740,| |812-970, 817-610, 817-955, 845-312, 845-890, 845-955, 848-990, 857-223, 860-551, 862-990,| |870-990, 903-540, 903-542, 903-772, 903-773, 903-775, 903-779, 903-837, 903-924, 903-936,| |903-974, 904-550, 904-970, 910-979, 914-480, 914-660, 914-780, 914-880, 914-910, 914-927,| |914-981, 914-982, 914-991, 917-220, 917-910, 979-259 and 980-952. | ----------------------------------------------------------------------------------------- Tired yet? Well, too bad; we still have a while to go! Toll-free numbering is, for whatever reason, entirely seperated from NANPA's grubby hands. A toll-free number (or "TFN") doesn't actually have an "exchange" per se, rather what's called an SAC. Following this nonstandard naming convention is that a toll-free "area code" is called, in a more reasonable fashion than whatever "SAC" means, an 8YY code. Given the lack of NANPA involvement, really anything goes. Somos, the organization responsible for 8YY numbering, has a few obvious ground rules like non being able to have 911 as an SAC, though this strangely doesn't apply to any other N11 codes other than the obvious 011 and 111 which wouldn't even be valid N11s in the first place. The usual justification for something like that would be for more vanity numbers to be valid, as in 1-800-COM-PANY or whatever, but 1 and 0 don't even map to any letters on a telephone keypad, so I guess they just let it fly out of boredom or something. 250 within every 8YY prefix is a test code; every resporg (responsible organization, essentially the "carrier" of a TFN) should typically have atleast one number within it that they can use for whatever testing purposes. This only applies for 250-0000 thru 250-1499, however. As previously mentioned, 555 is entirely valid in 800, but none of the other codes. Why they decided on this is beyond me. A similar sense of Somos being weirdly selective is evident with 800-855. This prefix is to be used exclusively in services for the hearing impaired, though this once again doesn't apply in any other 8YY. The LERG's General Info doc also gives us some insight into other reserved SACs, most are just specific geographical assignments however. As far as I'm aware, there are zero valid numbers in any of these prefixes as of now, but I may be wrong. They are as follows - 800-271 - Textel, Trinidad 800-389 - Batelco, Bahamas 800-415 - All American Cables, Dominican Republic 800-534 - Bartelco, Barbados 800-623 - Bermuda Tel Co, Bermuda 800-703 - For Future Assignment 800-740 - STSJ Telephone Co, Virgin Islands (in Non-US areas) 800-744 - Cable & Wireless 800-751 - Codetel, Dominican Republic 800-904 - For Future Assignment 800-907 - Tricom, Dominican Republic. That marks the end of everything I'm aware of that isn't valid as a telephone prefix. In any case, while working on this, I remembered a few things that I couldn't find anywhere to shove in. Here are some extra notes/facts on North American telephone numbering; ------------------------------------------------------------------------------------------- * Area code 710 is reserved for the federal government, specifically FEMA. It has one valid number, that being 627-4387, spelling out NCS-GETS. GETS is the Government Emergency Telecommunications System, effectively a fancy fed calling card platform that takes priority in the case of a disaster. * Area code 900, as mentioned earlier, is in use for premium rate communications services. In human terms; mostly sex, and also mostly defunct. * Area code 500 is reserved for personal communications services, not to be confused with PCS as a cellular technology. Effectively, the 1990s had telcos, mostly AT&T, offering "personal toll-free numbers" as an alternative to WATS service, or 800 numbers as they're referred to now. 700 played somewhat of a role in this too, though was less popular for such. The service didn't hang around for too long and most people lost their 500 numbers. Strangely, the NANPA continues to reserve and assign new PCS area codes pretty often! 500, 521, 522, 523, 524, 525, 526, 527, 528, 529, 532, 533, 535, 538, 542, 543, 544, 545, 546, 547, 549, 550, 552, 553, 554, 556, 566, 558, 569, 577, 578, 588 and 589 are all only to be used for this service. The reasoning is actually fairly interesting - certain devices that need to be used for communications services but often don't have an actual SIM tray, say an iPad for example, still need a "telephone number" assigned to themselves for various technical reasons. So, most of these number assignments don't actually get recognized by the general public almost ever nowadays. * Canada has a few of their own "special services" area codes. These are as follows - 600, 622, 633, 638, 644, 655, 677 and 688. * We're in quite the TFN drought right now. The next code to be assigned is 822, after that we'll start to assign "88Y" numbers; ie 880, 882, 883, etc. * Area codes 510, 610, 710, 810 and 910 were all previously reserved for TWX/Teletypewriter service. Western Union bought TWX from AT&T and they ended up dismantling the network in 1981. Since then, they've all been reassigned for use as standard geographic NPAs, other than 710 of course. * As of recent, and I mean VERY recent, it seems that a pager company (Spok, to be specific) has managed to buy up the 958 test prefix in a few areas. How they managed this and the routing trickery that must've been involved is beyond me.