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The North American Numbering Plan (NANP) is an integrated telephone numbering plan of 24 countries and territories: the United States and its territories, Canada, Bermuda, and 16 of the Caribbean countries.

The NANP is a system of numbering plan areas (NPA) with three-digit area codes and seven-digit telephone numbers that directs telephone calls to particular regions on a public switched telephone network (PSTN), where they are further routed by the local network.

Contents 1 Current system 2 Dialing plans 3 Charges 4 History 5 Calls to Mexico (until 1991) 6 Expansion of area codes 6.1 Splits and overlays 6.2 Expansion issues 6.3 Decrease in expansion rate 7 Alphabetic mnemonic system 8 Cellular services and the NANP numbering scheme 9 New area codes outside the U.S. and Canada 10 Fictional telephone numbers 11 Future expansion of NANP 12 Special numbers and codes 13 List of NANPA countries and territories 14 See also 15 References 16 External links

[edit] Current system

Developed in 1947, and first implemented in 1951 by AT&T, the NANP set out to simplify and facilitate direct dialing of long distance calls. Area code 201 was the first implemented under the plan.^[1] The NANP initially applied only to the U.S. and Canada, but at the request of the British Colonial Office, it was expanded to Bermuda and the British West Indies (including Trinidad and Tobago), due to their historic telecommunications administration through Canada as parts of the British Empire - and also their continued associations with Canada, especially during the years of the telegraph and the All Red Line system.

Despite the "North American" name of the calling plan, Mexico, the Central American countries and some Caribbean countries (Cuba, Haiti, the French, and Dutch-speaking Caribbean) are currently not part of the system; the nations of Mexico and Cuba formerly were. The only Spanish-speaking country in this plan is the Dominican Republic. Mexican participation was planned and partly implemented (with about two area codes assigned), with direct dialing from the NANP to some parts of Mexico through 1991.

The NANP is administered by the North American Numbering Plan Administration (NANPA).

Current NANP number format can be summed up via the following:

• NPA NXX Station

where

• NPA (Numbering Plan Area code) = [2-9][0-8][0-9]
• NXX (Central Office or Exchange code) = [2-9][0-9][0-9]
• Station code = [0-9][0-9][0-9][0-9]

For example:

• 234 234 5678 is valid
• 123 234 5678 is invalid, because NPA cannot begin with a "1"

The country calling code for the NANP is 1. In international format, an NANP number should be listed thus: +1 301 555 0100 (example using the Maryland area code). "1" is also the code often used to make direct-dialed long-distance calls within the NANP.

Each three-digit area code may contain up to 7,919,900 unique phone numbers:

• NXX may begin only with the digits [2-9], providing a base of 8 million numbers: ( 8 x 10^2 x 10^4 ) .
• However, the last two digits of NXX cannot both be 1, to avoid confusion with the N11 codes (subtract 80,000).
• Despite the widespread usage of NXX "555" for fictional telephone numbers — see 555 (telephone number) — today, the only such numbers specifically reserved for fictional use are "555-0100" through "555-0199", with the remaining "555" numbers released for actual assignment (subtract 100).

[edit] Dialing plans

Dialing plans vary from place to place depending on whether an area has overlays (multiple area codes serving the same area) and whether the jurisdiction requires toll alerting (a leading 1 for toll calls). The NANPA's web site includes dialing plan information in its information on individual area codes.

In areas without overlays and without toll alerting, calls within an area code are dialed as seven digits (7D), and calls outside the area code are dialed as 1 followed by 10 digits (1+10D). Most areas allow permissive dialing of 1+10D even for calls that could be dialed as 7D. The number of digits dialed is unrelated to whether a call is local or toll.

In areas with overlays, local calls are all dialed as 10D. In areas without toll alerting, all calls to numbers within the caller's area code and overlay codes serving the same area can be dialed as either 10D or 1+10D, while calls to other area codes must be 1+10D. In areas with toll alerting, all toll calls must be dialed as 1+10D. Most areas permit local calls to be dialed as 1+10D except for Texas and some jurisdictions in Canada which require that callers know which numbers are local and which are toll, dialing 10D for all local calls and 1+10D for all toll calls.

[edit] Charges

Despite the similar dialing format, calls between different countries and territories that use the NANP are not necessarily charged as domestic. Calls between the US and Canada are treated as international, although typically charged at lower rates than calls to other countries. Calls to other destinations in the NANP area can be high; for example, it generally costs more to call Bermuda from the US than it does to call the UK or Japan, even though the dialing format is the same as the domestic format. Similarly, calls from Bermuda to US numbers, (including toll-free 1-800), incur high international rates. This was because many of the island nations at the time implemented a plan of subsidizing the cost of local phone services by directly charging heavier pricing levies on the international Long Distance services.

On account of these higher fees, a handful of scams had taken advantage of customers' unfamiliarity with pricing structure to call the legacy regional 809 area code. Some scams lured customers from the U.S. and Canada into placing expensive calls to the Caribbean, by representing the area code (809) as a regular domestic, low-cost, or toll-free call. These scams are currently on the decline, with many of the Cable and Wireless service monopolies being opened up to competition, hence bringing rates down. Additionally many Caribbean territories have implemented local government agencies to regulate telecommunications rates of providers.^[2][3]

[edit] History

In order to facilitate direct dialing calls, the NANP was created and instituted in 1947 by AT&T, also known as the Bell System, the U.S. telephone semi-monopoly. At first, the codes were used only by long-distance operators; the first customer-dialed calls using area codes did not occur until November 10, 1951, when the first directly-dialed call was made from Englewood, New Jersey to Alameda, California.^[4] Direct dialing was gradually instituted throughout the country, and by the mid-1960s, it was commonplace in most larger cities.

Originally there were only 86 codes, with the biggest population areas getting the numbers that took the shortest time to dial on rotary telephones.^[5] That is why New York City was given 212, Los Angeles given 213, Chicago 312, and Detroit 313, while Vermont received 802 (a total of 20 clicks, 8+10+2). Four areas received the then-maximum number of 21 clicks: South Dakota (605), North Carolina (704), South Carolina (803), and Nova Scotia/Prince Edward Island in the Canadian Maritime Provinces (902). Additionally, in the original plan a middle digit of zero generally indicated the number was for an entire state or province with one area code, while a middle digit of one indicated that it was for a smaller region.

At first, area codes were all in the form N-Y-X, where N is any number 2-9, Y is 0 or 1, and X is any number 1-9 (if Y is 0) or any number 2-9 (if Y is 1). The restriction on N saves 0 for calling the operator, and 1 for signaling a long-distance call. The restriction on the second digit, limiting it to 0 or 1, was designed to help telephone equipment recognize the difference between a three-digit "area code" (with 0 or 1 as the second digit) and the three-digit "exchange" prefix (which had avoided 0 or 1 for the second digit, due to restrictions in existing switching equipment). For example, when a caller dialed "1-202-555-1212", the switching equipment would recognize that "202" was an area code because of the middle 0, and route the call appropriately. If a caller were to dial 1-345-6789, the 4 would be recognized as a long-distance call within the area code and routed as such, without waiting to see or guessing at how many digits the caller meant to enter.

In the late 1980s and early 1990s, NANPA (then still part of Bellcore, which is now Telcordia Technologies) began to urge and later require all long-distance calls within each area to include the code, so that badly-needed prefixes with 0 or 1 in the middle could be assigned to local telephone exchanges. Also, since it had nearly run out of area codes using the above formula, it allowed the assignment of area codes using the form N-1-0, such as 210 in the San Antonio, Texas, area and 410 in eastern Maryland.

[edit] Calls to Mexico (until 1991)

Until 1991, calls to some areas of Mexico from the United States and Canada were made using the North American Numbering Plan area codes. For example, to call a number in northwest Mexico and Mexico City before 1991:

• 1 905 Nxx xxxx (Mexico City)
• 1 706 Nxx xxxx (northwest Mexico) (prior to 1980, the code was 903, rather than 706)

From 1991, Mexican participation in the NANP was discontinued in favor of the general international format, and then the Area Code 905 was assigned to the Greater Toronto, Canada, area, just outside of Toronto, and the Area Code 706 was reassigned to northern Georgia, surrounding the Atlanta region (404):

• +52 5 xxx xx xx (Mexico City; now +52 55 xx xx xx xx (eight-digit local number, land line))
• +52 5 xxx xx xx (Mexico City; now +52 1 55 xx xx xx xx (eight-digit local number, cellular phone))
• +52 6 xxx xx xx (northwestern Mexico; now +52 6xx xxx xx xx, land line)
• +52 6 xxx xx xx (northwestern Mexico; now +52 1 6xx xxx xx xx, cellular phones)

[edit] Expansion of area codes

The United States has experienced rapid growth in the number of area codes, particularly in the 1990s and early 2000s. There are two main reasons for this. First, there is the increasing demand for telephone services (particularly due to widescale adoption of fax, modem, and cellular phone communications). The second and more important reason is due to telecom deregulation of local telephone service in the United States beginning in the early to mid-1990s. At that time, the Federal Communications Commission began allowing telecommunication companies to compete with the incumbent local exchange carrier (usually by forcing the existing monopoly service provider to lease infrastructure to other local providers who then resold the service to consumers). However, due to the original design of the numbering plan and telephone switching network which assumed only a single provider, number allocations had to be made in 10,000-number blocks. Thus, anytime a new local service provider entered a certain market it would be allocated 10,000 numbers by default, even if the provider could obtain few (if any) customers. As more companies began requesting numbering allocations, this caused many area codes to begin exhausting their supply of available numbers (code "in jeopardy" in telecom jargon), and additional area codes were needed. In reality many of the new telecom ventures were not successful and while the number of area codes started increasing rapidly, this did not necessarily translate to a much larger number of actual telephone subscribers as large blocks of numbers lay unassigned to any "real" subscribers due to the 10,000-number block allocation requirement.

In general, area codes were added either as "splits" (in which an area code was divided into two or more regions, one retaining the older area code and the other areas receiving a new code), or "overlays", in which multiple area codes were assigned to the same geographical area. Subtle variations of these techniques have been used as well, such as "dedicated overlays" [in which the new overlaid area code was reserved for a particular type of service, such as cellular phones and pagers (the only true example of this was area code 917 in New York City)] and "concentrated overlays", in which some of the area retained a single area code, while the rest of the region received an overlay code.

After the remaining valid area codes were used up in expansion, in 1995 the rapid increase in the need for more area codes (both splits and overlays) forced NANPA to allow the digits 2-8 to be used as a middle digit in new area code assignments, with 9 being reserved as a "last resort" for potential future expansion. At the same time, local exchanges were allowed to use 1 or 0 as a middle digit. The first Area codes without a 1 or 0 as the middle digit were Area code 334 in Alabama and Area code 360 in Washington, which both began service on January 15, 1995. Area codes, or "numbering plan areas" ending in double digits, such as toll-free 800, 888, 877, and 866, personal 700 numbers, and high-toll 900 numbers, are reserved as easily-recognizable codes (ERCs) and are not issued to actual geographic areas. (Nevada was denied the "lucky" number 777 for this reason.)

[edit] Splits and overlays

By 1995, many cities in the United States and Canada had more than one area code, either through splitting the city into different areas (splits) or having more than one area code for the same geographical area (overlays). For example, in Manhattan, New York, subscribers' numbers had the NPA code 212, but two additional codes—first 917 (which initially was exclusively for cellular phones and pagers until that idea was struck down in a Federal court), then 646—were also introduced. This means that the area code must be dialed, even for local calls. In other areas, 10-digit or 11-digit dialing is now required for all local calls. The transition to 10-digit dialing typically starts with a permissive dialing phase in which both 7-digit and 10-digit dialing is optional. During this period, the transition is heavily publicized. After a period of several months, the mandatory dialing phase is introduced, in which 7-digit dialing no longer works. Atlanta, Georgia, was the first city in the United States to have mandatory 10-digit dialing throughout its metropolitan area, roughly coinciding with the 1996 Summer Olympic Games in Atlanta. Atlanta was used as the test case not only due to its size, but also because it enjoyed the world's largest fiber optic network at the time (five times that of New York at the time), and it was home to BellSouth (now part of AT&T), then the Southeastern Regional Bell Operating Company.

• 7-digit dialing: Nxx xxxx (NPA code not required)
• 10-digit dialing: NPA Nxx xxxx
• 11-digit dialing: 1 NPA Nxx xxxx

The overlap between area codes and exchange prefixes has occasionally produced some confusion because the three digits can be the same for both. Nashua, New Hampshire, for example, has a local exchange that begins 888, which is also an area code for toll-free calls. If somebody in Nashua means to call 1-888-555-1212 but forgets the initial "1," he or she will actually dial the local number 1-603-888-5551. This, however, is generally not a problem in major metropolitan areas with overlapping area codes, which were mandated by the FCC to dial all ten digits for all local calls so as not to give new numbers or telecommunications providers a "disadvantage."

[edit] Expansion issues

Depending on the techniques used for area code expansion, the effect on telephone users varies. In areas in which overlays were used, this generally avoids the need for converting telephone numbers, so existing directories, business records, letterheads, business cards, advertising, and "speed-dialing" settings can retain the same phone numbers, while the overlay is used for new number allocations. The primary impact on telephone users is the necessity of remembering and dialing 10- or 11-digit numbers when only 7-digit dialing was previously permissible.

The use of a splitting instead of an overlay generally avoids the requirement for mandatory area-code dialing, but at the expense of having to convert some of the numbers to the new Area Code. In addition to the requirements of updating records and directories to accommodate the new numbers, for efficient conversion this requires a period of "permissive dialing" in which both the new and old Area Codes of the splitting are allowed to work. Also, in many splittings there were significant technical issues involved, especially when the Area Code splittings occurred over boundaries other than phone network divisions.

As an extreme example of an Area Code splitting gone somewhat awry, in 1998 the Minneapolis-St. Paul Twin Cities, which until that point used just the 612 area code, split into the 612 and 651 Area Codes, with St. Paul and the eastern metropolitan area receiving the new 651 Area Code. However, the Minnesota Public Utilities Commission mandated that the boundary of this splitting exactly follow municipal boundaries (which were distinctly different from telephone exchange boundaries), and that all subscribers keep their 7-digit numbers. These two goals were directly at odds with the reason for the Area Code splitting (to generate additional phone numbers), and there were more than 40 exchanges whose prefix territory straddled town boundaries along the Area Code splitting. The result was prefixes duplicated in both Area Codes, which counteracted much of the benefit of the splitting, with only 200 of 700 prefixes in the 612 Area moving entirely to the 651 Area. As a result, in less than two years the 612 Area Code again exhausted its supply of phone numbers, and it underwent another three-way split in the year 2000 - creating the new 763 and 952 Area Codes. Again, the split followed political boundaries rather than rate center boundaries, resulting in additional split prefixes, and in a few cases resulted in numbers initially moved to the 651 Area Code being moved again to the 763 Area Code in less than two years.

[edit] Decrease in expansion rate

Recognizing that the major cause in the proliferation of area codes was due to the telecom deregulation act and the 10,000 number block assignment, the FCC instructed NANPA (by then administered by NeuStar) to look for a solution to alleviate the numbering shortage. As a result a new program called "number pooling" was piloted in 2001 which allowed allocating numbers in 1,000-number blocks rather than 10,000 numbers. Due to the design of switched telephone network, this was a considerable technical challenge and was carried out together with another technically-challenging program, local number portability. Since then the program has been rolled out to most parts of the United States and together with aggressive reclamation of unused number blocks from telecom providers, the need for additional area codes has been reduced, so much so that the implementation of large numbers of previously designated area splits and overlays has been postponed indefinitely.

[edit] Alphabetic mnemonic system

Another oddity of NANP telephone numbering is the use of alphabetic dialing. On most US and Canadian telephones, three letters appear on each number button from 2 through 9 (as standardized much later by ISO 9995-8 and, in Europe, E.161). This accommodates 24 letters. Historically, the letters Q and Z were omitted, though on some modern telephones, they are added, so that the alphabet is apportioned as follows:

 2 = ABC
 3 = DEF
 4 = GHI
 5 = JKL
 6 = MNO
 7 = PRS or PQRS
 8 = TUV
 9 = WXY or WYZ or WXYZ

No letters are allocated to the 1 or 0 keys (although some corporate voice mail systems are set up to count Q and Z as 1, and some old telephones assigned the Z to the digit 0).

Originally, this scheme was meant as a mnemonic device for telephone number prefixes. When telephone numbers in the US were standardized in the mid-20th century, they were made seven digits long, including a two-digit prefix, the latter expressed as letters rather than numbers. (Before World War II, a few localities used three letters and four numbers; in most cities with customer dialing, phone numbers had only six digits — two letters followed by four numbers.) The prefix was a name, and the first two or three letters (usually shown in capitals) of the name were dialed. Later, the third letter (where previously used) was replaced by a number, or an extra number was added; this generally happened after World War II, although New York City did this in 1930. Thus, the famous Glenn Miller tune "PEnnsylvania 6-5000" refers to a telephone number 736-5000, the number of the Hotel Pennsylvania, which still bears the same number today. Similarly, the classic Elizabeth Taylor film "BUtterfield 8" refers to the section of New York City where the film is set, where the telephone prefixes include 288 (on the East Side of Manhattan between roughly 64th and 86th Streets). This is why, in some works of fiction, phone numbers will begin with "KLondike 5" or "KLamath 5", which translates to 555, a mostly unused and reserved exchange. This practice continues in film and television to this day, even though the prefix system has long been unused.

Today this system has been abandoned (it was phased out starting in the early 1960s, though it persisted in some places as late as the mid-1970s), but alphabetic dialing remains as a commercial mnemonic gimmick, particularly when combined with toll-free numbers. For example, one can dial 1-800-FLOWERS to send flowers to someone, or 1-800 DENTIST to find a local dentist. Sometimes, longer phonewords are used - for example one might be invited to give money to a public radio station by dialing 1-866-KPBS-GIVE. The "number" is 8 digits long, but only the first seven need be dialed. If an eighth (or more) digit is dialed, the switching system will ignore it. Mobile users may need to manually drop any numbers past the seventh digit as some mobile switching systems will not automatically ignore them, resulting in a failed call. In addition to commercial uses, alphabetic dialing has influenced, in rare cases, the choice of regional area codes in the United States. For example, when East Tennessee was split into two area codes in 1999, the region surrounding Knoxville received a new code; the code 865 was chosen to represent the word "VOL"—short for "Volunteers", the nickname of athletic teams at the University of Tennessee. Likewise, when the 606 area code of central and eastern Kentucky was split, Lexington, the region's largest city, adopted the new code 859 (which spells UKY) in honor of the University of Kentucky. The Miami area originally had the 305 area code, but then 786 was added due to the increasing demand for telephone numbers. 786 spells out SUN in honor of Florida being the Sunshine State. 352 is used around Gainesville, Florida, north of Tampa and northwest of Orlando and spells FLA again as a nod to the state. The area around Cape Canaveral, Florida, was split from area code 407 and became area code 321. This represented the launch of a rocket, specifically 3-2-1-Blastoff! The State of Nevada has previously attempted to obtain area code 777 (lucky 7's), but was unable to secure it.^[6] When the Dayton, Ohio area split from the Cincinnati, Ohio Area code 513, literature promoting the new area code 937 took advantage of the fact that the numbers spelled "YES".

See Telephone number#Alphanumeric trivia

[edit] Cellular services and the NANP numbering scheme

A difference between the NANP system and other plans is that apart from area code 600 in Canada, no separate, non-geographical area codes have been created for cellular phones, as is the case in most European and Asian countries, where mobile services are assigned their own prefixes. This means that most North American mobile phones are assigned the same locality-specific codes as landlines, and calls to them are billed at the same rate. Consequently, the caller-pays pricing model adopted in other countries, in which calls to cellular phones are charged at a higher nationwide rate, but receiving calls is free, could not be used. Instead, North American cellular telephone users are also generally charged to receive calls as well (subscriber pays). In the past, this discouraged mobile users from using the phones or giving out the number. However, robust price competition among carriers has led to dramatic cuts in the average price per minute for contract customers (for both inbound and outbound calls), which can compare favorably to those in caller-pays countries. Most users select bundle pricing plans that include all the minutes they expect to use in a month, and many carriers offer first inbound minute free or in some cases, entirely free inbound calling.

Some industry observers have blamed user pays as one of the main factors in the relatively low penetration rate of mobile telephony in the United States compared to that of Europe. However, in the wireless-subscriber-pays model the convenience of the mobility is charged to the subscriber, which many users regard as a fairer pricing system. Callers from outside the local-calling region of the assigned number are, however, forced to pay for a long-distance call, although domestic long distance rates are generally lower than the rates caller-pays systems charge (conversely, an advantage of caller-pays is the relative absence of telemarketing and nuisance calls to mobile numbers). The integrated numbering plan also enables local number portability between fixed and wireless services within a region, allowing users to switch to mobile service while keeping their phone number, which is not a common option in caller-pays systems.

The initial plan for overlays did allow for providing separate area codes for use by mobile phones, faxes, pagers, etc., although these were still assigned to a specific geographical area, rather than the nationwide mobile area codes common to most other countries, and were charged at the same rate as other area codes. Initially, the new 917 area code for New York City was specifically assigned for this purpose within the 5 boroughs; however, a Federal court struck this down and banned the use of an area code for a specific telephony purpose. Since mobile telephony is expanding faster than landline, new area codes typically have a disproportionately large fraction of mobile numbers, although landline and other services rapidly follow and local network portability can blur these distinctions.

The experience of Hurricane Katrina and similar events revealed a possible disadvantage of the methods employed in the geographic assignment of cellular numbers. Many mobile phone users could not be reached, their phones rendered inoperable, even when they were far from the stricken areas, because the routing of calls to their phones depended on equipment in the affected area. A hypothetical caller-pays system with separate numbers would not have required geographical routing, although the existing system could have been designed to avoid this problem as well.

Another related issue for services like mobile telephony is the scarcity of telephone numbers. In contrast to other countries, where mobile and other special-number operators enjoy wide leeway to generate large numbers of telephone numbers, this is not an option in the NANP, with its geographical area codes with a fixed number of digits. Because of the scarcity of telephone numbers, the market value of each is consequently higher. This has been cited by mobile operators as another factor putting pressure on the development of cellular services, and of pay-as-you-go in particular, although the decreasing rate at which new telephone numbers are being allocated suggests that other factors may be at work.

[edit] New area codes outside the U.S. and Canada

Prior to 1995, all other NANP countries and territories outside the fifty United States and Canada, including Puerto Rico and the US Virgin Islands, shared the NPA code 809, but they are now able to have separate codes. Code (809) is now only used by the Dominican Republic. In 1997 the United States Pacific Territories of the Northern Marianas and Guam became part of the NANP, as did American Samoa in October 2004.

Bermuda:

• Until 1995: +1 809 29x xxxx
• After 1995: +1 441 (xxx) xxxx

Puerto Rico:

• Until 1996: +1 809 xxx xxxx
• 1996-2001: +1 787 xxx xxxx
• After 2001: +1 787 xxx xxxx or +1 939 xxx xxxx (overlay for entire island)

US Virgin Islands:

• Until 1997: +1 809 xxx xxxx
• After 1997: +1 340 xxx xxxx

Northern Marianas:

• Until 1997: +670 xxx xxxx
• After 1997: +1 670 xxx xxxx

Guam:

• Until 1997: +671 xxx xxxx
• After 1997: +1 671 xxx xxxx

American Samoa:

• Until October 1, 2004: +684 xxx xxxx
• After October 2, 2004: +1 684 xxx xxxx

See also: Split from the 809 Area code

[edit] Fictional telephone numbers

In American television shows and films, 555 (or, in older movies and shows, KLondike 5 or KLamath 5) is used as the first three digits of fictional telephone numbers, so if anyone is tempted to telephone a number seen on screen, it does not cause a nuisance to any actual person.

There are occasions, however, when a non-555 is used in real-life context, with varying intents and consequences. A classic example of such is the 1982 song "867-5309/Jenny" by Tommy Tutone, which is still the cause of a large number of nuisance calls. Similarly, the song "Diary" by Alicia Keys says to call "489-4608 and I'll be here." It was intended to be called only by people in New York to get her voicemail. At the time that it was recorded in the late 1970s, the B-52s song "6060-842" could not result in a nuisance call, because telephone prefixes could not employ zero as the second digit. Since then, however, the rules governing prefix morphology have changed, causing 606-0842 to become a valid telephone number. In 2003, the movie Bruce Almighty caused controversy because God contacts Bruce, via pager, using an actual phone number 776-2323. The DVD and television versions changed the display of the pager to 555-0123. Another example was when a version of Madonna: Truth or Dare showed Madonna giving out her actual phone number. The phone number was quickly changed and the scene was cut from the movie shortly afterwards. In movies that took place in New York City in the 1940's to the 1960's, numbers like "PLaza 3-9970", "BOwling green 3-9970" or "PLaza 3-5598" were used. At that time, the Public Switched Telephone Network in New York City utilized mainly mechanical switches such as Panel and #1 crossbar and those were "test numbers" that always rang to a busy signal.

Similarly, not all numbers beginning with "555" are fictional. For example, 555-1212 is the number for directory assistance in many places. In many, but not all areas, dialing "555" numbers other than 555-1212 will actually get you to directory assistance as well. In fact, only 555-0100 through 555-0199 are now reserved for fictional use, with the other numbers having been released for assignment. Since "1xx" exchanges are generally not assigned, some movies have started to use fictional telephone numbers starting with "1", giving someone a "telephone number" of 167-1402 in one film, for example.

[edit] Future expansion of NANP

The North American Numbering Plan Administration (NANPA) is now overseen by NeuStar Inc., which will probably face the task of adding one or two digits to each number, likely sometime after 2038^[7]. During that time, all public and private phone systems on this continent will have to be upgraded and reprogrammed (or even replaced) to recognize the new dialing rules.

The plans being considered now add a 1 or 0 either to the beginning or end of the area code, or the beginning of the local 7-digit number (or both), which will require mandatory 10-digit dialing (even for local calls), between any two NANP numbers, well before the transition period. In another proposal, existing codes would be changed to "n9xx" (e.g. San Francisco's 415 would become 4915); once that conversion is complete, the new second digit would be opened for a new range. (Compare PhONE Day in the United Kingdom, which added a "1" to the beginning of area codes in preparation for later using other digits, such as "2", for new area codes.) Other proposals include reallocating blocks of numbers assigned to smaller long distance carriers or unused reserved services.

NANPA previously coordinated an expansion of long-distance carrier access ("dial-around") codes from five digits (such as 10-321) to seven (10-10-321), in 1998. Vertical service codes, such as *69 (callback) and *70 (suspend call waiting), have been designed to allow the use of both two- and three-digit codes.

[edit] Special numbers and codes

Some common special numbers in the North American system:

• 0 - Operator assistance
• 00 - Long distance operator assistance
• 011 - International Access Code. (For all destinations outside the NANP)
• 01 - International Access Code using operator assistance. (For all destinations outside the NANP)
• 10x xxxx - Used to select use of an alternative long-distance carrier
• 211 - Community information or social services (In some cities), formerly payphone refund line (and prior to that, used to access "long distance" operators in some cities)
• 311 - City government or non-emergency police matters such as noise complaints, suspicious people, minor injuries and non-working streetlights and parking meters, etc. (In some cities)
• 411 - Local telephone directory service (Some telephone companies provide national directory assistance)
• 511 - Traffic, road, and tourist information or reads back the number you are calling from (i.e. drop line ID) (In some cities and states)
• 611 - Telephone line repair service (Some telephone companies use this instead of 4104 or 811). Also used by mobile telephone companies to reach customer service
• 711 - Relay service for customers with hearing or speech disabilities
• 811 - "Dig safe" underground pipe safety line in the United States, non-urgent telehealth services in Canada, formerly telephone company business office, mainly to encourage people not to hit telephone or power lines when they dig.
• 911 - Emergency dispatcher for fire department, ambulance, police etc.
• 830 or 958 or 9580 or 998 - Returns the number on the line via a recorded voice (in some areas)
• (Area Code) + 555-1212 - Non-local directory service

There are also special codes, such as:

• *51 A history of unanswered calls on a telephone number, useful for those who are not Caller-ID subscribers.
• *57 and 1157 (per-use fee.) Used to "trace" harassing, threatening, abusive, obscene, etc. phone calls, and keep results of trace at phone company.)
• *66 and 1166 To keep retrying a busy-line (see also Called-party camp-on)
• *67 and 1167 Caller ID Block
• *69 and 1169 Call Return caller may press '1' to return call after hearing number
• *70 and 1170 Cancel call waiting on a call-by-call basis
• *71 and 1171 Three way calling, which lets a person to talk to people in two different locations at the same time.
• *74 and 1174 Speed dialing, which allows someone to quickly dial any of eight frequently called numbers using a one-digit code, from any phone on their line. *75 allows a total of 30 speed-call numbers.
• *82 and 1182 Releases Caller ID block on a call-by-call basis

Note: The four digit numbers do not work in some areas. The codes prefixed with the "*" symbol are intended for use on Touch-Tone telephones, whereas the four-digit numbers prefixed 11xx are intended for use on older rotary dial telephones, where the Touch-Tone * symbol is not available.

Not all NANPA countries use the same codes. For example, the emergency telephone number is not always 911: Trinidad and Tobago uses 999, as in the United Kingdom. The country of Barbados uses 211 for police force, 311 for fire, and 511 for ambulance, while Jamaica uses 114 for directory assistance, 119 for police force, and 110 for fire and ambulance services.

Despite its early importance as a share of the worldwide telephone system, few of the NANP's codes, such as 911, have been adopted outside the system. Determining that 911 requires unnecessary rotation time on rotary dial telephones, the European Union has adopted its own standardized number of 112, while countries in Asia and the rest of the world use a variety of other two- or three-digit emergency telephone number combinations. The 112 code is gaining prevalence due to its preprogrammed presence in mobile telephones that conform to the European GSM standard. The European Union and many other countries have chosen the International Telecommunication Union's 00 as their international access number instead of 011. The toll-free prefix 800 has been widely adopted elsewhere, including as the international toll-free number. It is often preceded by a 0 rather than a 1 in many countries where 0 is the trunk prefix.

[edit] List of NANPA countries and territories

• Antigua and Barbuda
• Bahamas
• Barbados
• Canada
• Dominica
• Dominican Republic
• Grenada
• Jamaica
• Saint Kitts and Nevis
• Saint Lucia
• Saint Vincent and the Grenadines
• Trinidad and Tobago
• The following possessions of the United Kingdom:
  • Anguilla
  • Bermuda
  • British Virgin Islands
  • Cayman Islands
  • Montserrat
  • Turks and Caicos Islands
• United States, including:
  • Guam
  • Northern Mariana Islands
  • Puerto Rico
  • U.S. Virgin Islands
  • American Samoa

[edit] See also

• List of NANP area codes
• List of country calling codes
• Bell System
• Vertical service code

[edit] References

[edit] External links

• North American Numbering Plan Administration (NANPA)

• Caribbean numbering plan for several islands in the NANP

• Map of the original 86 area codes from 1947
• Animation of US area codes since 1947
• North American Numbering Council
• Instant NPA+NXX Lookups