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'{{short description|Integrated telephone numbering plan serving 20 North American countries}} {{Redirect|NANPA|other uses|Nanpa (disambiguation)}} [[File:NANP countries.svg|thumb|Countries participating in the North American Numbering Plan]] The '''North American Numbering Plan''' ('''NANP''') is a [[telephone numbering plan]] that encompasses twenty-five distinct regions in twenty countries primarily in [[North America]], including the [[Caribbean]]. Some North American countries, most notably [[Mexico]], do not participate in the NANP. The NANP was originally devised in the 1940s by [[AT&T Corporation|AT&T]] for the [[Bell System]] and independent telephone operators in North America to unify the diverse local numbering plans that had been established in the preceding decades. AT&T continued to administer the numbering plan until the [[breakup of the Bell System]], when administration was delegated to the North American Numbering Plan Administrator (NANPA), a service that has been procured from the private sector by the [[Federal Communications Commission]] (FCC) in the [[United States]]. Each participating country forms a regulatory authority that has [[plenary power|plenary control]] over local numbering resources.<ref>{{cite web|url=http://www.nanpa.com/contact_us/NANP_Country_Contacts.pdf|publisher=Neustar|format=PDF|title=Contacts in the Countries Participating in the North American Numbering Plan}}</ref> The FCC also serves as the U.S. regulator. Canadian numbering decisions are made by the [[Canadian Numbering Administration Consortium]].<ref>{{cite web|url=http://www.cnac.ca/cnac/cna_consortium.htm|title=Canadian Numbering Administrator}}</ref> The NANP divides the territories of its members into '''numbering plan areas''' ('''NPAs''') which are encoded numerically with a three-digit telephone number prefix, commonly called the [[area code]].<ref>{{cite web|title=NANPA : Number Resources - NPA (Area) Codes|url=http://www.nanpa.com/area_codes/|accessdate=2015-10-23}}</ref> Each telephone is assigned a seven-digit [[telephone number]] unique only within its respective plan area. The telephone number consists of a three-digit [[telephone exchange|central office]] code and a four-digit station number. The combination of an area code and the telephone number serves as a destination routing address in the [[public switched telephone network]] (PSTN). For international call routing, the NANP has been assigned the [[international calling code]] 1 by the [[International Telecommunications Union]] (ITU). The North American Numbering Plan conforms with ITU Recommendation [[E.164]], which establishes an international numbering framework.<ref>{{cite web|title=The International Public Telecommunication Numbering Plan|url=https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-E.164-201011-I!!PDF-E&type=items|publisher=ITU|accessdate=2015-07-25|author=ITU|author2=ITU-T}}</ref> ==History== From its [[History of the telephone|beginnings]] in 1876 and throughout the first part of the 20th century, the [[Bell System]] grew from essentially local or regional telephone systems. These systems expanded by growing their subscriber bases, as well as increasing their service areas by implementing additional local exchanges that were interconnected with [[tie trunk]]s. It was the responsibility of each local administration to design telephone numbering plans that accommodated the local requirements and growth.<ref name=bstj1952>{{cite journal |last1=Nunn |first1=W. H. |year=1952 |title=Nationwide Numbering Plan |journal=Bell System Technical Journal |volume=31 |issue=5 |pages=851–9 |doi=10.1002/j.1538-7305.1952.tb01412.x}}</ref> As a result, the Bell System as a whole developed into an unorganized system of many differing local numbering systems. The diversity impeded the efficient operation and interconnection of exchanges into a nationwide system for long-distance telephone communication. By the 1940s, the Bell System set out to unify the various numbering plans in existence and developed the North American Numbering Plan as a unified, systematic approach to efficient long-distance service that eventually did not require the involvement of switchboard operators. The new numbering plan was officially accepted in October 1947, dividing most of North America into eighty-six numbering plan areas (NPAs). Each NPA was assigned a numbering plan area code, often abbreviated as ''area code''. These codes were first used by long-distance operators to establish long-distance calls between toll offices. The first customer-dialed direct call using area codes was made on November 10, 1951, from [[Englewood, New Jersey]], to [[Alameda, California]].<ref>[http://www.corp.att.com/attlabs/reputation/timeline/51trans.html 1951: First Direct-Dial Transcontinental Telephone Call], [[AT&T Corporation]]. Accessed 2007-06-08. "Nov. 10, 1951: Mayor M. Leslie Downing of Englewood, N.J., picked up a telephone and dialed 10 digits. Eighteen seconds later, he reached Mayor Frank Osborne in Alameda, Calif. The mayors made history as they chatted in the first customer-dialed long-distance call, one that introduced area codes."</ref> [[Direct distance dialing]] (DDD) was subsequently introduced across the country. By the early 1960s, most areas of the Bell System had been converted and DDD had become commonplace in cities and most larger towns. In the following decades, the system expanded to include all of the [[United States]] and its [[Insular area|territories]], [[Canada]], [[Bermuda]], and seventeen nations of the [[Caribbean]].<ref>{{cite web|url=http://www.nanpa.com/about_us/index.html|title=NANPA: North American Numbering Plan Administration - About Us|publisher=}}</ref><ref>{{cite news|last=Mehta|first=Stephanie N.|title=The Kennedy Space Center Acquires A New Area Code: 3-2-1, as in Blast Off |newspaper=[[The Wall Street Journal]] |date=1999-02-26}}</ref> By 1967, 129 area codes had been assigned.<ref name=att1968>AT&T, ''Notes on Distance Dialing'' (1968).</ref> At the request of the [[Colonial Office|British Colonial Office]], the numbering plan was first expanded to [[Bermuda]] and the [[British West Indies]] because of their historic telecommunications administration through [[Canada]] as parts of the [[British Empire]] and their continued associations with Canada, especially during the years of the telegraph and the [[All Red Line]] system.{{Citation needed|date=December 2018}} Not all North American countries participate in the NANP. Exceptions include [[Mexico]], [[Greenland]], [[Saint Pierre and Miquelon]], the [[Central America]]n countries and some [[Caribbean]] countries ([[Cuba]], [[Haiti]], and the [[French Caribbean]]). The only [[Spanish-speaking countries|Spanish-speaking state]] in the system is the [[Dominican Republic]]. Mexican participation was planned,<ref name=ATT1980>AT&T, ''Notes on the Network'', Section 3, p.8 (1980)</ref> but implementation stopped after three area codes (706, 903 and 905) had been assigned, and Mexico opted for an international numbering format, using country code 52.<ref>[https://books.google.co.uk/books?id=-tstAQAAIAAJ&focus=searchwithinvolume&q=52 ''Green book''], Volume 2, Part 1, International Telegraph and Telephone Consultative Committee, International Telecommunication Union, 1973, page 129</ref> The area codes in use were subsequently withdrawn in 1991. Area code 905, formerly used for Mexico City, was reassigned to a split of area code 416 in the [[Greater Toronto Area]]; area code 706, which had formerly served Mexico's [[Baja California peninsula|Baja Peninsula]], was reassigned to a portion of northern [[Georgia (U.S. state)|Georgia]]<ref>{{cite web|url=https://articles.latimes.com/1991-01-31/local/me-23_1_area-code |title=Phone System Changes Kill 2 of Mexico's Area Codes - latimes |date=18 October 2015 |url-status=bot: unknown |archiveurl=https://web.archive.org/web/20151018150017/http://articles.latimes.com/1991-01-31/local/me-23_1_area-code |archivedate=2015-10-18 }}</ref> surrounding the [[Atlanta]] region, which retained 404; and area code 903, which served a small portion of northern Mexico, was reassigned to [[Area codes 430 and 903|northeastern Texas]] when it split from [[area code 214]].{{citation needed|date=December 2018}} The Dutch Caribbean territory of [[Sint Maarten]] joined the NANP in September 2011, receiving [[area code 721]].<ref name="Sint Maarten delay"/> Sint Maarten shares the island with the French [[Collectivity of Saint Martin]] which, like the rest of the French Caribbean, is not part of the NANP. ==Administration== The NANP is administered by the ''North American Numbering Plan Administrator'' (''NANPA'')<ref>{{cite web|url=https://nationalnanpa.com/|title=NANPA:North American Numbering Plan Administrator|publisher=[[Somos, Inc.]]|access-date=May 4, 2020|url-status=live|archive-url=https://web.archive.org/web/20200430092502/https://nationalnanpa.com/|archive-date=April 30, 2020}}</ref><ref>{{cite web|url=https://nationalnanpa.com/about_us/index.html|title=NANPA:North American Numbering Plan Administrator - About Us|publisher=[[Somos, Inc.]]|access-date=May 4, 2020|url-status=live|archive-url=https://web.archive.org/web/20200219122755/https://nationalnanpa.com/about_us/index.html|archive-date=February 19, 2020}}</ref> (formerly ''Administration'').<ref>{{cite web|url=http://www.nanpa.com/index.html|title=NANPA:North American Numbering Plan Administration|publisher=Neustar|url-status=dead|archive-url=https://web.archive.org/web/20151113025425/http://www.nanpa.com/index.html|archive-date=November 13, 2015}}</ref><ref>{{cite web|url=http://www.nanpa.com/about_us/abt_nanp.html|title=About the North American Numbering Plan|publisher=Neustar|url-status=dead|archive-url=https://web.archive.org/web/20151210073643/http://www.nanpa.com/about_us/abt_nanp.html|archive-date=December 10, 2015}}</ref> Today, this function is overseen by the [[Federal Communications Commission]], which assumed the responsibility upon the breakup of the Bell System. The FCC solicits private sector contracts for the role of the administrator. Initially, the service was provided by a division of [[Lockheed Martin]] in 1997. In 1999, the contract was awarded to [[Neustar|Neustar Inc.]], a company spun off from Lockheed for this purpose. In 2004 and again in 2012, the contract was renewed with Neustar.<ref>{{cite web|url=http://www.nanpa.com/about_us/index.html|title=About NANPA|publisher=Neustar|accessdate=2015-06-23}}</ref> On January 1, 2019, [[Somos, Inc.|Somos]] assumed the NANPA function under a new contract granted by the FCC.<ref>https://www.somos.com/insights/somos-inc-awarded-north-american-numbering-plan-administration-and-pooling-administration-contracts</ref> ==Numbering plan== The vision and goal of the architects of the North American Numbering Plan was a system by which telephone subscribers in the United States and Canada could themselves dial and establish a [[telephone call]] to any other subscriber without the assistance of [[switchboard operator]]s. While this required an expansion of most existing local numbering plans, many of which required only four or five digits to be dialed, or even fewer in small communities, the plan was designed to enable local telephone companies to make as few changes as possible in their systems. The intent was that most subscribers should not have to dial a long, full national telephone number to make a local telephone call.{{Citation needed|date=December 2018}} ===Numbering plan areas and central offices{{anchor|numbering plan area}}=== The new numbering plan divided the North American continent into regional service areas, each called a numbering plan area (NPA), primarily following the jurisdictional boundaries of [[U.S. states]] and [[Canadian provinces]].<ref name=att1955 /> States or provinces could be divided into multiple areas. NPAs were created in accordance with principles deemed to maximize customer understanding and minimize dialing effort while reducing plant cost.<ref name=ATTnotes>''[[Notes on the Network]]'', AT&T (1980)</ref> Each NPA was identified by a unique three-digit code number, that was prefixed to the local telephone number. Existing [[telephone exchange]]s and central offices became local exchange points in the nationwide system, each of which was assigned a unique three-digit number unique within its NPA. The combination of NPA code and central office code served as a destination routing code for use by operators and subscribers to reach any central office through the switching network.<ref name=att1955>AT&T (1955) ''Notes on Nationwide Dialing''</ref> Due to the structure of the numbering plan, each NPA was technically limited to 540 central offices.<ref name=ATTnotes /> This limitation to 540 central offices required the most populous states to be divided into multiple NPAs. [[New York (state)|New York]] state was initially divided into five areas, the most of any state. [[Illinois]], [[Ohio]], [[Pennsylvania]], and [[Texas]] were assigned four NPAs each, and [[California]], [[Iowa]], and [[Michigan]] received three. Eight states and provinces were split into two NPAs. These divisions attempted to avoid cutting across busy toll traffic routes, so that most toll traffic remained within an area, and outgoing traffic in one area would not be tributary to toll offices in an adjacent area.<ref name=nunn>W.H. Nunn, ''Nationwide Numbering Plan'', Bell System Technical Journal 31(5), 851 (1952)</ref><ref name=att1955 /> Traditionally, subscribers were assigned four-digit numbers, meaning that each central office could serve up to ten thousand subscriber numbers. Thus the new numbering plan identified each telephone in the system with the combination of area code, central office code, and line number, resulting in a closed [[telephone numbering plan]] with a ten-digit national telephone number for each telephone.<ref name=closednp>AT&T, ''Notes on the Network'', Section 10, p.3 (1980).</ref> The leading part of this address was the area code (three digits), followed by the seven-digit subscriber number consisting of three digits for the central office and four digits for the station. The intent was for subscribers not to have to dial an area code when making a local call or a call within their plan area, resulting in [[seven-digit dialing]]. Area codes were only required in [[ten-digit dialing]] when placing ''foreign area'' calls to subscribers in another state or numbering plan area.<ref>{{cite web|url=https://mentalfloss.com/article/61116/why-did-old-phone-numbers-start-letters|title=Why Did Old Phone Numbers Start With Letters?|author=John Greene|date=January 16, 2015|publisher=Mental Floss|accessdate=February 1, 2019}}</ref> ===Initial numbering system=== The new network design, completed in 1947, provided for 152 area codes, each with a capacity to serve 540 central offices.<ref name=ATTnotes /> Originally only [[List of original NANP area codes|86 area codes]] were assigned. [[New Jersey]] received the first area code in the new system, [[Area codes 201 and 551|area code 201]].<ref>[http://scholar.lib.vt.edu/VA-news/VA-Pilot/issues/1995/vp951101/11010459.htm "Now You Can Call, If Your Calls Don't Work Some Business Lines Aren't Set Up To Call To New Area Codes"] {{webarchive|url=https://web.archive.org/web/20080316221411/http://scholar.lib.vt.edu/VA-news/VA-Pilot/issues/1995/vp951101/11010459.htm |date=2008-03-16 }}, ''[[The Virginian-Pilot]]'', November 1, 1995. Accessed June 8, 2007. "When the first area code, 201, was introduced in New Jersey in 1951, phone-numbering experts thought there would be enough codes with a middle digit of ''0'' or ''1'' to last well into the next century."</ref> The second area code, [[area code 202|202]], was assigned to the [[District of Columbia]]. The allocation of area codes was readjusted as early as 1948 to account for inadequacies in some metropolitan areas. For example, the [[Indiana]] numbering plan area [[area code 317|317]] was divided to provide a larger numbering pool in the Indiana suburbs of [[Chicago]] ([[area code 219]]).{{citation needed|date=December 2018}} Initially, states divided into multiple numbering plan areas were assigned area codes with the digit ''1'' in the second position, while areas that covered entire states or provinces received codes with ''0'' as the middle digit. This rule was abandoned by the early 1950s.<ref name=att1955 /> To provide for automatic distinction of seven-digit dialing from ten-digit dialing in switching systems, central office codes were restricted to not having a ''0'' or ''1'' in the middle position. This was already common practice, because in the system of using the first two letters of [[central office name|familiar names for central offices]] did not assign letters to digits ''1'' and ''0''. Furthermore, area codes and central office codes could also not start with ''0'' or ''1'', because ''0'' was used for [[operator assistance]] and a leading single pulse, as if produced by the digit ''1'', was automatically ignored by most switching equipment of the time.<ref name=att1955 /> In addition, the eight codes of the form ''N11'' (''N = 2–9'') were reserved as service codes.<ref name=att1968 /> The easily recognizable codes of the form ''N00'' were available in the numbering plan, but were not initially included in assignments.{{Citation needed|date=December 2018}} Additional area code patterns were later assigned for other services; for example, the area codes ''N10'' were implemented for the [[Telex|Teletypewriter Exchange Service]] (TWX).<ref>{{cite book|url=https://books.google.com./books?id=u1Y-AQAAMAAJ&pg=PA516&lpg=PA516&dq=Teletypewriter+Exchange+Service+N-10&source=bl&ots=NBaPxxylxc&sig=ACfU3U1VnE270UYIYg8k0tSD7-jUkzh25g&hl=en&sa=X&ved=2ahUKEwjV-picyprgAhUNhrwKHfASCtQQ6AEwE3oECAEQAQ#v=onepage&q=Teletypewriter%20Exchange%20Service%20N-10&f=false|title=Statistical Abstract of the United States|year=1960|pages=516|accessdate= February 1, 2019}}</ref> The central office code was chosen such that it could be represented by the first two letters of the [[telephone exchange name|central office name]] according to a digit-to-letter mapping that was printed on the face of a rotary dial, by grouping a set of letters with the digits ''2'' through ''9''. Such letter translations, designed by W.G. Blauvelt in 1917, had been used in the Bell System in large metropolitan areas since the late 1910s.<ref>Bell Telephone Laboratories, ''A History of Engineering and Science in the Bell System - The Early Years (1875-1925)'', M.D. Fagan (ed.), 1975, p.126</ref> The network reorganization eventually resulted in a two-letter, five-digit (2L-5N) representation of telephone numbers for every exchange in North America.{{Citation needed|date=December 2018}} ===Plan of 1960=== <!-- To be completed... --> The original plan of 1947 had been projected to be usable beyond the year 2000. However, by the late 1950s it became apparent that it would be outgrown by about 1975.{{Citation needed|date=December 2018}} ===Modern plan=== In the late 1980s and early 1990s, the NANPA implemented calling procedures that required all long-distance calls within an area code to be prefixed with the area code, in an effort to make it possible to assign central-office prefixes with 0 or 1 in the middle position (except for ''N11''), which would otherwise be wrongly taken by the local [[telephone switch]] to be the area code. As it had nearly run out of area codes using the existing assignment methods, this expanded the number pool for each area code by nearly twenty-five percent and also allowed for the later addition of area codes with middle digits other than 0 or 1.{{Citation needed|date=December 2018}} Requiring a 1 to be dialed before the full number in some areas also provided for area codes of the form ''N10'', such as 210 in the [[San Antonio]], Texas, area and 410 in eastern [[Maryland]]. Therefore, someone calling from [[San Jose, California]], to [[Los Angeles]] before the change would have dialed 213-555-0123 and after the change 1-213-555-0123, which permitted the use of 213 as an exchange prefix in the San Jose area. The preceding 1 also ideally indicates a [[long-distance calling|toll call]]; however, this is inconsistent across the NANP because the FCC has left it to the [[U.S. state]] [[public utilities commission]]s to regulate for traditional [[landline]]s, and it has since become [[Mootness|moot]] for [[mobile phone]]s and digital [[VoIP]] services that now offer nationwide calling without the extra digit.{{citation needed|date=December 2018}} The NANP number format may be summarized in the notation ''NPA-NXX-xxxx'': {| class=wikitable ! Component ! Name ! Number ranges ! Notes |- | NPA |Numbering plan area code |Allowed ranges: [2–9] for the first digit, and [0-9] for the second and third digits. When the second and third digits of an area code are the same, that code is called an easily recognizable code (ERC). ERCs designate special services; e.g., 888 for toll-free service. The NANP is not assigning area codes with 9 as the second digit.<ref>{{cite web|url=http://www.nanpa.com/area_codes/index.html |title=NANPA : Number Resources - NPA (Area) Codes|publisher=}}</ref> |Covers Canada, the United States, parts of the Caribbean Sea, and some Atlantic and Pacific islands. The area code is often enclosed in parentheses. |- | NXX |[[telephone exchange|Central office]] (exchange) code |Allowed ranges: [2–9] for the first digit, and [0–9] for both the second and third digits (however, in geographic area codes the third digit of the exchange cannot be ''1'' if the second digit is also ''1''). |Central office code: Within the NPA a uniquely assigned three-digit code. It is often considered a part of the subscriber number. |- |xxxx |Line number or subscriber number |[0–9] for each of the four digits. |Within a central office, a unique four-digit number, also called ''station code''. |} For example, ''234-235-5678'' is a valid telephone number with area code 234, central office prefix (exchange) 235, and line number 5678. The number ''234-911-5678'' is invalid, because the central office code must not be in the form N11. ''314-159-2653'' is invalid, because the office code must not begin with ''1''. ''123-234-5678'' is invalid, because the NPA must not begin with 0 or 1.{{Citation needed|date=December 2018}} The [[country calling code]] for all countries participating in the NANP is ''1''. In international format, an NANP number should be listed as {{gaps|+1|999|555|0100}}, where ''999'' stands in for the area code. Each three-digit area code has a capacity of 7,919,900 telephone numbers: * NXX may begin only with the digits [2–9], providing a base of eight million numbers: (8 × 100 × 10000). * However, to avoid confusion with the [[N11 code]]s, the last two digits of NXX cannot both be 1.{{citation needed|date=February 2016}} * Despite the widespread usage of NXX ''555'' for [[555 (telephone number)|fictional telephone numbers]], the only such numbers now specifically reserved for fictional use are ''555-0100'' through ''555-0199''. The remaining ''555'' numbers are presently unavailable for assignment. * In individual geographic area codes, several other NXX prefixes are generally not assigned: the home area code(s), adjacent domestic area codes and overlays, area codes reserved for future relief nearby, industry testing codes (generally NXX 958 and 959) and special service codes (such as NXX 950 and 976).{{Citation needed|date = April 2018}} Various office codes in certain plan areas are deliberately not issued; for example, numbers {{gaps|212|718-xxxx}}, where 212 and 718 are both [[New York City]] area codes, are typically avoided to prevent confusion between an area code and a similarly numbered local exchange in the same region. 958-xxxx and 959-xxxx are usually test numbers. Using 0 or 1 as the first digit of an area code or seven-digit local number is invalid, as is a 9 as the middle digit of an area code; these are trunk prefixes or reserved for [[North American Numbering Plan expansion]]. Lists of exchanges in an individual area code (posted by CNAC in Canada, NANP in the United States) all list various prefixes as deliberately not issued.{{Citation needed|date = April 2018}} ===International dialing=== While the national numbering plan of the NANP was designed as a 10-digit closed plan, international direct distance dialing (IDDD) was accomplished by extensive modifications in switching systems to accommodate an open international numbering plan for telephone numbers from seven to twelve digits.<ref>AT&T, ''Notes on the Network'', Section 10.3.02, p.3 (1980).</ref> ==Expansion== {{refimprove section|date=February 2014}} Canada and the United States have experienced rapid growth in the number of area codes, particularly between 1990 and 2005. The widespread adoption of [[fax]], [[modem]], and [[mobile phone]] communication, as well as the deregulation of local telecommunication services in the United States in the mid-1990s, increased the demand for telephone numbers. The Federal Communications Commission allowed telecommunication companies to compete with the [[incumbent local exchange carrier]]s for services, usually by forcing the existing sole service provider to lease infrastructure to other local providers. Because of the original design of the numbering plan and the telephone switching network that assumed only a single provider, number allocations had to be made in 10,000-number blocks even when much fewer numbers were required for each new vendor. Due to the proliferation of service providers in some numbering plan areas, many area codes fell into ''jeopardy'', facing exhaustion of numbering resources. The number blocks of failed service providers often remained unused, as no regulatory mechanism existed to reclaim and reassign these numbers. Area codes are added by two principal methods, number plan area ''splits'' and ''[[overlay plan]]s''. Splits were implemented by dividing an area into two or more regions, one of which retained the existing area code and the other areas receiving a new code. In an overlay, multiple codes are assigned to the same geographical area, obviating the need for renumbering of existing services. Subtle variations of these techniques have been used as well, such as ''dedicated overlays'', in which the new code is reserved for a particular type of service, such as cellular phones and pagers, and ''concentrated overlays'', in which a part of the area retained a single code while the rest of the region received an overlay code. The only service-specific overlay in the NANP was [[area code 917]] (New York City) when it was first installed; such service-specific area code assignments were later prohibited by the Federal Communications Commission. Most area codes of the form N10, originally reserved for AT&T's [[Teletypewriter eXchange]] (TWX) service, were transferred to Western Union in 1969 and were freed up for other use in 1981 after conversion to [[Telex|Telex II]] service was complete. The last of these, [[area code 600|610]], was assigned to Canada, but reassigned in 1992. These new area codes, as well as a few other codes used for routing calls to Mexico, were used for telephone area code splits in the late 1980s and early 1990s, as all other area codes under the original plan had been consumed. After the remaining valid area codes were used up by expansion, in 1995 the rapid increase in the need for more area codes forced the NANPA to allow the digits 2 through 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. This was quickly followed by [[area code 520]] serving Arizona on March 19, 1995. Codes ending in double digits are reserved as ''easily recognizable codes'' (ERCs), to be used for special purposes such as toll-free numbers, personal [[area code 500|500]] numbers, Canadian non-geographic [[area code 600]], carrier-specific [[area code 700|700]] numbers, and high-toll [[900 number]]s, rather than for geographic areas. Nevada was denied 777 ("lucky 7s", a reference to the state's legalized gambling) for this reason;<ref>{{cite web|url=http://vegasinc.com/business/2012/jul/19/new-area-code-being-considered-las-vegas/|title=Additional area code being considered for Las Vegas|date=19 July 2012|publisher=}}</ref> it received [[area code 775|775]] instead when most of Nevada split from [[area code 702|702]], which continues to serve the [[Las Vegas–Paradise, NV MSA|Las Vegas metropolitan area]]. By 1995, many cities in the [[United States]] and [[Canada]] had more than one area code, either from dividing a city into different areas (NPA split) or having more than one code for the same area (NPA overlay). The overlay method requires that the area code must be dialed in all cases, even for local calls, while the split plan may permit seven-digit dialing within the same area. The transition to ten-digit dialing typically starts with a permissive dialing phase, which is widely publicized, during which dialing all ten digits is optional. After a period of several months, mandatory dialing begins, when seven-digit dialing is no longer permissible. [[Atlanta]] was the first U.S. city to require mandatory ten-digit dialing throughout the metropolitan area, roughly coinciding with the [[1996 Summer Olympics]] held there. Atlanta was used as the test case not only because of its size, but also because it had the world's largest fiber optic network at the time, five times larger than that of [[New York City|New York]], and it was home to [[BellSouth]] (now part of AT&T), then the Southeastern [[Regional Bell Operating Company]], with AT&T's fiber optics manufacturing facility within the city. {| class=wikitable style="float:right;" ! colspan=3 | Common dialing methods |- |7-digit dialing||NXX xxxx || NPA code not required |- |10-digit dialing||NPA NXX xxxx || |- |11-digit dialing||1 NPA NXX xxxx || ''1'' is the NANP trunk prefix for long-distance circuits |} ===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. Splitting instead of overlaying generally avoids the requirement for mandatory area-code dialing, but at the expense of having to convert a region to the new 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 the new and old codes are both allowed to work. Also, many splittings involved significant technical issues, especially when the area splittings occurred over boundaries other than phone network divisions. In 1998 [[area code 612]], which had covered the [[Minneapolis – Saint Paul]] Twin Cities, was split to create [[area code 651]] for [[Saint Paul, Minnesota|St. Paul]] and the eastern metropolitan area. The [[Minnesota Public Utilities Commission]] mandated that the new boundary 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 split, namely to provide additional phone numbers. More than 40 exchanges had territory that straddled the new boundary. As a result, prefixes were duplicated in both area codes, which counteracted much of the benefit of the splitting, with only 200 of 700 prefixes in area 612 moving entirely to area 651. In less than two years area code 612 again exhausted its supply of phone numbers, and required a three-way split in 2000, creating the new [[area code 763|area codes 763]] and [[area code 952|952]]. Again, the split followed political boundaries rather than rate center boundaries, resulting in additional split prefixes; a few numbers moved from 612 to 651 and then to 763 in less than two years. ===Decrease in expansion rate=== Recognizing that the proliferation of area codes was largely due to the telecom regulation act and the assignment of numbers in blocks of 10,000, the FCC instructed NANPA, by then administered by [[Neustar]], to alleviate the numbering shortage. As a result, [[number pooling]] was piloted in 2001 as a system for allocating local numbers to carriers in blocks of 1,000 rather than 10,000. Because of the then design of the switched telephone network, this was a considerable technical obstacle. Number pooling was implemented with another technical obstacle, [[local number portability]]. The program has been implemented in much of the United States by state regulators. A limited number of cities have also implemented rate center consolidation; fewer rate centers resulted in more efficient use of numbers, as carriers would reserve blocks of 1,000 or 10,000 numbers in each of multiple rate centers in the same area even if they had relatively few clients in the area.<ref>http://www.nanpa.com/number_resource_info/Summary-of-Rate-Center-Consolidations.pdf</ref> (A rate center is a geographical area used by a Local Exchange Carrier (LEC) to determine the boundaries for local calling, billing and assigning phone numbers. Typically a call within a rate center is local, while a call from one rate center to another is a long-distance call.) Together with aggressive reclamation of unused number blocks from telecom providers, number pooling has reduced the need for additional area codes, so that many previously designated area splits and overlays have been postponed indefinitely. There is no number pooling in Canada. Number allocation remains highly inefficient as even the tiniest village is a rate center and every [[Competitive local exchange carrier|CLEC]] is assigned blocks of ten thousand numbers in every place it offers new local service. As a result, dialing seven digits even in remote locations like [[James Bay]] is more likely to produce an [[intercept message]] ("''dial the area code''") than an actual voice connection. ===New area codes outside the contiguous United States and Canada=== Before 1995, all NANP countries and territories outside the [[contiguous United States]], Alaska, Hawaii and Canada shared the area code 809. This included [[Puerto Rico]] and the [[United States Virgin Islands|U.S. Virgin Islands]]. Each has since been assigned one or more distinct numbering plan areas; area code [[Telephone numbers in the Dominican Republic|809]] now exclusively serves the [[Dominican Republic]] (along with area codes 829 and 849). The United States Pacific territories of the [[Northern Mariana Islands]] and [[Guam]] joined the NANP in 1997, and [[American Samoa]] became an NANP member in October 2004. The Dutch possession of [[Sint Maarten]] was originally scheduled to join the NANP on May 31, 2010, but the changeover was postponed to September 30, 2011.<ref name="Sint Maarten delay"/> {| class=wikitable |Bermuda || before 1995: served by area code 809 || 1995: assigned area code 441 |- |Puerto Rico || before 1996: served by area code 809 || 1996: assigned area code 787 2001: overlaid with area code 939 |- |U.S. Virgin Islands || before 1997: served by area code 809 || 1997: assigned area code 340 |- |Northern Marianas || before 1997: reached via IDDD using country code 670 || 1997: assigned area code 670 |- |Guam || before 1997: reached via IDDD using country code 671 || 1997: assigned area code 671 |- |American Samoa || before Oct. 1, 2004: reached via IDDD using country code 684 || 2004: assigned area code 684 |- |Sint Maarten || before Sept. 30, 2011: reached via IDDD using country code 599 || 2011: assigned area code 721 |} ===Number size expansion=== {{Main article|North American Numbering Plan expansion}} The NANP exhaust analysis estimates that the existing numbering system is sufficient beyond 2049, based on the assumptions that a maximum of 674 NPAs continue to be available, and that on average 3990 central office codes are needed per year.<ref>{{cite web|url=https://nationalnanpa.com/reports/April_2019_NANP_Exhaust_Analysis_Final.pdf|title=April 2019 North American Numbering Plan (NANP) Exhaust Analysis|author=|date=|website=nationalnanpa.com}}</ref> In case of exhaustion, various plans are discussed for expanding the numbering plan. One option is to add the digit 1 or 0 either at the beginning or at the end of the area code, or prefixing it to the seven-digit subscriber number. This would require eleven-digit dialing even for local calls between any two NANP numbers. Another proposal introduces the digit ''9'' into the area code in the format ''x9xx'', so that, for example, [[San Francisco]]'s ''415'' would become ''4915''. Other proposals include reallocating blocks of numbers assigned to smaller long-distance carriers or unused reserved services.{{citation needed|date=June 2015}} =={{anchor|List of NANPA countries and territories}}Countries and territories== Of all states or territories, the U.S. state of California has the largest number of area codes assigned, followed by Texas, Florida and New York, while most countries of the Caribbean use only one.<ref>{{Cite web|url=https://www.areacodehelp.com/acus/us_area_codes.shtml|title=United States Area Codes|website=www.areacodehelp.com|access-date=2018-09-27}}</ref> Many [[Area codes in the Caribbean|Caribbean codes]] were assigned based on alphabetic abbreviations of the territory name, as indicated in the third column of the following table (''Letter code''). This follows the traditional [[#Alphabetic mnemonic system|letter assignments]] on telephone dials. For some Pacific islands, the NANPA area code is the same as the [[List of country calling codes|country code]] that was discontinued upon membership in the NANP. {| class=wikitable ! Country/Territory || Area codes || Letter code |- |{{Flag|American Samoa}} || [[Area code 684|684]]* || |- |{{Flag|Anguilla}} || [[Area code 264|264]] || ANG |- |{{Flag|Antigua and Barbuda}} || [[Area code 268|268]] || ANT |- |{{Flag|Bahamas}} || [[Area code 242|242]] || BHA |- |{{Flag|Barbados}} || [[Area code 246|246]] || BIM |- |{{Flag|Bermuda}} || [[Area code 441|441]] || |- |{{Flag|British Virgin Islands}} || [[Area code 284|284]] || BVI |- |{{Flagicon|Canada}} [[Telephone numbers in Canada|Canada]] || [[Area code 204|204]], [[Area code 226|226]], ... [[Area code 905|905]] || |- |{{Flag|Cayman Islands}} || [[Area code 345|345]] || |- |{{Flag|Dominica}} || [[Area code 767|767]] || ROS ([[Roseau]]) |- |{{Flag|Dominican Republic}} || [[Telephone numbers in the Dominican Republic|809]], [[Telephone numbers in the Dominican Republic|829]], [[Telephone numbers in the Dominican Republic|849]] || |- |{{Flag|Grenada}} || [[Area code 473|473]] || GRE |- |{{Flag|Guam}} || [[Area code 671|671]]* || |- |{{Flag|Jamaica}} || [[Area code 876|876]], [[Area code 658|658]]<ref>{{cite web|url=http://jamaica-gleaner.com/article/lead-stories/20170828/call-658-jamaica-gets-additional-area-code-10-digit-dialling-becomes|title=Call 658 ... Jamaica gets additional area code, 10-digit dialling becomes mandatory May 2018|author=|date=|website=jamaica-gleaner.com}}</ref> || |- |{{Flag|Montserrat}} || [[Area code 664|664]] || |- |{{Flag|Northern Mariana Islands}} || [[Area code 670|670]]* || |- |{{Flag|Puerto Rico}} || [[Telephone numbers in Puerto Rico|787]], [[Telephone numbers in Puerto Rico|939]] ||PUR (787) |- |{{Flag|Saint Kitts and Nevis}} || [[Area code 869|869]] || |- |{{Flag|Saint Lucia}} || [[Area code 758|758]] || SLU |- |{{Flag|Saint Vincent and the Grenadines}} || [[Area code 784|784]] || SVG |- |{{Flag|Sint Maarten}}<ref name="Sint Maarten delay">{{cite web|url=http://www.nanpa.com/pdf/PL_418.pdf |title=PL-418: Introduction of NPA 721 (Sint Maarten) |publisher=North American Numbering Plan Administration |date=2011-01-05 |accessdate=2011-08-08}} Updated by: {{cite web|url=http://www.nanpa.com/pdf/PL_423.pdf |title=PL-423: Updated Information - Introduction of NPA 721 (Sint Maarten) |publisher=North American Numbering Plan Administration |date=2011-07-27 |accessdate=2011-08-08}}</ref> || [[Area code 721|721]] || |- |{{Flag|Trinidad and Tobago}} || [[Area code 868|868]] || TNT |- |{{Flag|Turks and Caicos Islands}} || [[Area code 649|649]] || |- |{{Flag|United States}} || [[Area code 201|201]], [[Area code 202|202]], ... [[Area code 989|989]] || |- |{{Flag|United States Virgin Islands}} || [[Area code 340|340]] || |- | ||colspan=2 style="text-align:left;"|* same as previous country code |} ==Dialing procedures== The structure of the North American Numbering Plan permits implementation of local [[dial plan]]s in each plan area, depending on requirements. When multiple NPA codes serve an area in an overlay arrangement, ten-digit (10D) dialing is required. Seven-digit (7D) dialing may be permissible in areas with single area codes.<ref>{{cite web|url=http://www.nanpa.com/enas/npaDialingPlansReport.do|title=Uniform Dialing Plans|publisher=}}</ref> Depending on the requirement of toll alerting, it may be necessary to prefix a telephone number with ''1''. The NANPA publishes dial plan information for individual area codes.<ref>{{cite web|url=https://www.nationalnanpa.com/enas/npasRequiring10DigitReport.do|title=Area Codes Requiring 10 Digit Dialing|publisher=}}</ref> The standard dial plans in most cases are as follows: {| class=wikitable ! ! Local within area code ! Local outside area code ! Toll within area code ! Toll outside area code |- |Single code area, with toll alerting |7D |7D or 10D |1+10D |1+10D |- |Single code area, without toll alerting |7D |1+10D |7D or 1+10D |1+10D |- |Overlaid area, with toll alerting |10D |10D |1+10D |1+10D |- |Overlaid area, without toll alerting |10D or 1+10D |1+10D |10D or 1+10D |1+10D |} The number of digits dialed is unrelated to being a local call or a toll call when there is no toll alerting. Allowing 7D local dial across an area code boundary, which is uncommon today, requires [[central office code protection]], locally if using toll alerting, across the entire area code otherwise, to avoid assignment of the same seven-digit number on both sides. Most areas permit local calls as 1+10D except for Texas, Georgia, and some jurisdictions in Canada which require that landline callers know which numbers are local and which are toll, dialing 10D for local calls and 1+10D for all toll calls. In almost all cases, domestic operator-assisted calls are dialed 0+10D. ===Special numbers and codes=== Some common special numbers in the North American system: * 0 – [[Operator assistance]] * 00 – [[Long-distance operator]] assistance (formerly 2-1-1) * [[011]] – International access code using direct dial (for all destinations outside the NANP). * 01 – International access code using operator assistance (for all destinations outside the NANP). * 101-xxxx – Used to select use of an alternative [[interexchange carrier|long-distance carrier]] * [[2-1-1|211]] – Local community information or social services (in some cities) * [[3-1-1|311]] – City government or non-emergency police matters * [[4-1-1|411]] – Local telephone directory service (Some telephone companies provide national directory assistance) * [[5-1-1|511]] – Traffic, road, and tourist information * [[6-1-1|611]] – Telephone line repair service (formerly 4104), [[Mobile network operator|wireless operator]] customer service (formerly 811). * [[7-1-1|711]] – Relay service for customers with hearing or speech disabilities. * [[8-1-1|811]] – ''Dig safe'' pipe/cable location in the United States, non-urgent [[telehealth]]/teletriage services in Canada (formerly telephone company business office) * [[9-1-1|911]] – [[Emergency telephone number]] – fire department, medical emergency, police. * 950-xxxx – [[Feature group]] code for access to a carrier from a non-subscriber location. The feature requires the customer dial a 950-xxxx number and enter a calling card number and destination telephone number. It was originally used for locations where 101-xxxx dialing was not possible. * 958-xxxx (local); 959-xxxx (long distance) – [[Plant test number]]s, such as [[automatic number announcement circuit]]s. It was once common to reserve entire unused exchange prefixes or N11 numbers (4101 was ringback on many step-by-step switches), but these have largely moved to individual unpublished numbers within the standard 958-xxxx (local) or 959-xxxx (long-distance) plant test exchanges as numbers become scarce. * 1-NPA-555-1212 – Non-local directory information (Canada and United States) * In December 2019, the [[Federal Communications Commission]] proposed making 9-8-8 a national number in the United States for the [[National Suicide Prevention Lifeline]].<ref>[https://www.cnn.com/2019/12/12/politics/fcc-988-suicide-prevention-hotline/index.html FCC unanimously approves proposal for new 3-digit number as Suicide Prevention Hotline]</ref> There are also [[Vertical service code|special codes]], such as: * *51 and 1151: A history of unanswered calls on a telephone number, useful for those who are not [[Caller ID]] subscribers. * *57 and 1157: Used to [[Call tracing|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 talk to people in two different locations at the same time. * *74 and 1174: Speed dial, 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 with two digits. * *77 activates Anonymous Call Rejection Service * *82 and 1182: Releases Caller ID block on a call-by-call basis * *87 deactivates Anonymous Call Rejection Service '''Note''': The four-digit numbers are not implemented in some areas. The codes prefixed with an asterisk (*) symbol are intended for use on [[Touch-Tone]] [[telephone]]s, whereas the four-digit numbers prefixed 11xx are intended for use on [[rotary dial telephone]]s, where the [[Touch-Tone]] '''*''' symbol is not available. Not all NANP countries use the same codes. For example, the [[emergency telephone number]] is not always 911: [[Trinidad and Tobago]] and [[Dominica]] use [[999 (emergency telephone number)|999]], as in the [[United Kingdom]]. The country of [[Barbados]] uses 211 for [[police]] force, 311 for [[fire station|fire]], and 511 for [[ambulance]], while [[Jamaica]] uses 114 for directory assistance, 119 for [[police]] force, and 110 for [[fire station|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 [[1-1-2|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 because of 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 country code. It is often preceded by a 0 rather than a 1 in many countries where 0 is the [[trunk prefix]]. ==Alphabetic mnemonic system== {| class=wikitable style="float:right;" ! digit || letters | rowspan=9| [[File:Telephone keys.JPG|thumbnail|Letters of the alphabet are mapped to the digits of the telephone dial pad.]] |- |2 ||ABC |- |3 ||DEF |- |4 ||GHI |- |5 ||JKL |- |6 ||MNO |- |7 ||P(Q)RS |- |8 ||TUV |- |9 ||WXY(Z) |- |} Many dials on modern telephones in use in the NANP service areas maintain the tradition of alphabetic dialing. Usually each pushbutton from digit 2 to 9 also displays three letters, which is standardized in [[ISO/IEC 9995|ISO 9995-8]] and, in Europe, [[E.161]]. Historically, the letters Q and Z were omitted, although some modern telephones contain them. [[Short Message Service|SMS-capable]] devices have all 26 letters. The alphabet is apportioned to the buttons as follows: No letters are typically mapped to keys ''1'' and ''0'', although some corporate [[voicemail]] systems use 1 for Q and Z, and some old telephones assigned the Z to the digit 0. <!-- this should be refactored in historical sequence with previous content -->Originally, this scheme was used as a mnemonic device for telephone number prefixes. When telephone numbers in the United States were standardized in the mid-20th century to seven digits, the first two digits of the exchange prefix were expressed as letters rather than numbers, using the [[telephone exchange name]]. Before [[World War II]], the largest cities used three letters and four or five numbers, while in most cities with customer dialing, phone numbers had only six digits (2L-4N). The prefix was a name, and the first two or three letters, usually shown in capital letters, were dialed. Later, the third letter, where implemented, was replaced by a digit, or an extra digit was added. This generally happened after World War II, although [[New York City]] converted in 1930. The adoption of seven-digit local numbers (2L-5N) was chosen as the requirement for [[direct distance dialing]] and progressively deployed starting the late 1940s. The famous [[Glenn Miller]] tune ''[[PEnnsylvania 6-5000]]'' refers to telephone number PE6-5000, a number still in service at the [[Hotel Pennsylvania]] (212 736-5000) in New York. Similarly, the classic film ''[[BUtterfield 8]]'' is set in the East Side of [[Manhattan]] between roughly 64th and 86th Streets, where the telephone prefixes include 288. In some works of fiction, phone numbers will begin with "KLondike 5" or ''KLamath 5'', which translates to [[555 (telephone number)|555]], an exchange that is reserved for information numbers in North America. The letter system was phased out, beginning before 1965, although it persisted ten years later in some places. It was included in [[Bell of Pennsylvania]] directories until 1983. Even today, some businesses still display a 2L-5N number in advertisements, e.g., the Belvedere Construction Company in [[Detroit]], [[Michigan]] not only still uses the 2L-5N format for its number (TYler 8-7100), it uses the format for the toll-free number (1-800-TY8-7100). Despite the phasing out of the letter system otherwise, alphabetic [[phoneword]]s remain as a commercial [[mnemonic]] gimmick, particularly for toll-free numbers. For example, one can dial [[1-800-Flowers|1-800-FLOWERS]] to order flowers, or 1-800-DENTIST to find a local dentist. In addition to commercial uses, alphabetic dialing has occasionally influenced the choice of regional area codes in the United States. For example, when [[area code 423|area 423]] ([[East Tennessee]]) was split in 1999, the region surrounding [[Knoxville, Tennessee|Knoxville]] was assigned [[area code 865]], chosen to represent the word ''VOL'' (''Volunteers''), the nickname of [[Tennessee]] (''The Volunteer State''), as well as athletic teams at the [[University of Tennessee]].<ref>Brewer, Bill. [https://web.archive.org/web/19991003042549/http://areacode-info.com/headline/1999/tn990417.htm 423 Area Code To Become VOL In 9 ET Counties]. ''Knoxville News-Sentinel''. April 17, 1999.</ref><ref>[http://www.state.tn.us/tra/pressr/1999/vol865.pdf Tennessee Regulatory Authority press release], April 29, 1999</ref> Another example of this is [[area code 859]] in [[Kentucky]], which was chosen to represent 'UKY' as a nod to the [[University of Kentucky]] in [[Lexington, Kentucky]], the code's principal city. Several Caribbean area codes were chosen as an alphabetic abbreviation of the country name, which are indicated in the table of NANP regions. ==Cellular services== The North American Numbering Plan does not set aside special non-geographic area codes exclusively for [[cellular phones]]. Only one regional exception exists in [[area code 600]] in Canada. In many other national numbering plans outside the NANP, mobile services are assigned separate prefixes. Cell phone numbers in the NANP are allocated within each area code from special central office prefixes and calls to them are billed at the same rate as any other call. Consequently, the ''caller pays'' pricing model adopted in other countries, in which calls to cellular phones are charged at a higher nationwide rate, but incoming mobile calls are not charged to the mobile user, could not be implemented. Instead, North American cellular telephone subscribers are also generally charged for receiving calls (''subscriber pays''). This has discouraged mobile users from publishing their telephone number. However, price competition among carriers has reduced the average price per call minute for contract customers for both inbound and outbound calls, which compare favorably to those in caller-pays countries.{{citation needed|date=May 2015}} Most users select bundle pricing plans that include an allotment of minutes expected to be used in the billing period. Of the four major national carriers in the United States, all four ([[AT&T Mobility|AT&T]], [[T-Mobile US|T-Mobile]]/[[Sprint Corporation|Sprint]], [[Verizon Communications|Verizon]]) offer free calling between mobile phones on the carrier's network, and Sprint also offers its customers free calling to mobile phones on other networks.{{citation needed|date=May 2015}} Industry observers have attributed the relatively low [[mobile phone penetration rate]] in the United States, compared to that of Europe, to the subscriber-pays model.{{citation needed|date=May 2016}} In this model the convenience of the mobility is charged to the subscriber. Callers from outside the local-calling region of the assigned number, however, pay for a long-distance call, although domestic long-distance rates are generally lower than the rates in caller-pays systems. Conversely, an advantage of caller-pays is the relative absence of [[telemarketing]] and [[nuisance call]]s 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 telephone number. The initial plan for area code overlays did allow for providing separate area codes for use by mobile devices, although these were still assigned to a specific geographical area, and were charged at the same rate as other area codes. Initially, the area code 917 for [[New York City]] was specifically assigned for this purpose within the boroughs; however, a Federal court overturned the practice and the use of an area code for a specific telephony purpose.{{citation needed|date=August 2009}} Since mobile telephony has been expanding faster than landline use, new area codes typically have a disproportionately large fraction of mobile and nomadic 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, even when they were far from the stricken areas, because the routing of calls to their phones depended on equipment in the affected area. They could make calls but not receive them.<ref>NBC News, [https://www.nbcnews.com/id/9120503/ns/technology_and_science-tech_and_gadgets/t/katrina-outages-reveal-phone-system-quirks/ “Katrina outages reveal phone system quirks”], retrieved 14 Feb 2018.</ref> The use of geographic numbers may also lead to [[anti-tromboning|tromboning]]; one can take a handset with a [[Vancouver]] number into [[St. John's, Newfoundland and Labrador|St. John's]] and outbound calls to St. John's numbers while in that city will be local, but incoming calls must make the cross-country trip to Vancouver and back. This adds costs for subscribers, as an 8,000&nbsp;km cross-country call (as a worst case) incurs long-distance tolls in both directions. [[Advanced Mobile Phone System|AMPS]] subscribers used to be provided with a local number (such as 1-NPA-NXX-ROAM) in each city, allowing them to be reached by dialing that number plus the ten-digit mobile telephone number; this is no longer supported. ==Toll charges== Calls between different countries and territories of the NANP are not typically charged at domestic rates. For example, most long-distance plans may charge a California subscriber a higher rate for a call to British Columbia than for a call to New York, even though both destinations are within the NANP. Similarly, calls from Bermuda to U.S. numbers (including [[Toll-free telephone numbers in the North American Numbering Plan|1-800 numbers]], which are normally thought of as [[Toll-free telephone number|toll-free]]) incur international rates. This is because many of the island nations implemented a plan of subsidizing the cost of local phone services by directly charging higher pricing levies on international long-distance services.{{citation needed|date=May 2016}} Because of these higher fees, [[scam]]s had taken advantage of customers' unfamiliarity with pricing structure to call the legacy regional area code 809. Some scams lured customers from the United States and Canada into placing expensive calls to the [[Caribbean]], by representing area code [[Telephone numbers in the Dominican Republic|809]] as a regular domestic, low-cost, or toll-free call. The split of 809 (which formerly covered all of the Caribbean NANP points) into multiple new area codes created many new, unfamiliar prefixes which could be mistaken for U.S. or Canada domestic area codes but carried high tariffs. In various island nations, premium exchanges such as +1-876-HOT-, +1-876-WET- or +1-876-SEX- (where 876 is [[Jamaica]]) became a means to circumvent consumer-protection laws governing [[area code 900]] or similar U.S.-domestic premium numbers. These scams are on the decline, with many of the [[Cable & Wireless (Caribbean)|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.<ref>{{cite web|url=http://www.ftc.gov.bb/index.php?option=com_content&task=view&id=18&Itemid=45|title=Fair Trading Commission, Barbados - Legislation|first=|last=Administrator|publisher=}}</ref><ref>{{Cite web |url=http://www.ectel.int/telecoms-regulations.html |title=The Eastern Caribbean Telecommunications Authority (ECTEL) > Telecom regulations |access-date=2009-03-13 |archive-url=https://web.archive.org/web/20110718092807/http://www.ectel.int/telecoms-regulations.html |archive-date=2011-07-18 |url-status=dead }}</ref> ==Number portability== The [[Telecommunications Act of 1996]] ({{USC|47|251}} (b)(2)) authorizes the [[U.S. Federal Communications Commission|Federal Communications Commission]] (FCC) to require all [[local exchange carrier]]s (LECs) to offer [[local number portability]].<ref>11 [[FCC Record|FCC Rcd]] [https://digital.library.unt.edu/ark:/67531/metadc2049/m1/397/ 8353]</ref> The FCC regulations were enacted on June 27, 1996, with changes to take effect in the one hundred largest [[Metropolitan Statistical Area]]s by October 1, 1997 and elsewhere by December 31, 1998.<ref>11 [[FCC Record|FCC Rcd]] [https://digital.library.unt.edu/ark:/67531/metadc2049/m1/399/ 8355]. The regulations are located at {{USCFR|47|52|subpart=C}}, {{USCFR|47|52|20}} ''et seq.''</ref> The FCC directed the [[North American Numbering Council]] (NANC) to select one or more private-sector candidates for the local number portability administrator (LNPA) function,<ref>{{USCFR|47|1|1204}}</ref> in a manner akin to the selection of the North American Numbering Plan Administrator (NANPA).<ref>11 [[FCC Record|FCC Rcd]] [https://digital.library.unt.edu/ark:/67531/metadc2049/m1/445/ 8401]</ref> The [[toll-free telephone number]]s in NPA 800, 888, 877, 866, 855, and 844 have been portable through the [[RespOrg]] system since 1993.<ref>10 [[FCC Record|FCC Rcd]] [https://digital.library.unt.edu/ark:/67531/metadc2067/m1/368/ 12351]</ref> ==Fictional telephone numbers== American [[television program]]s and [[film]]s often use the [[555 (telephone number)|central office code 555]], or KL''amath'' 5 and KL''ondike'' 5 in older movies and shows, for [[fictitious telephone number]]s, to prevent disturbing actual telephone subscribers if anyone is tempted to dial a telephone number seen or referred to on screen. Occasionally, valid telephone numbers are used in contexts such as songs with varying intents and consequences. An example is the [[1981 in music|1981]] song "[[867-5309/Jenny]]" by [[Tommy Tutone]], which is the cause of a large number of calls.<ref>{{cite web |date= July 9, 2014 |url= http://www.snopes.com/music/songs/8675309.asp |work= Urban Legends Reference Pages |publisher= snopes.com |title= '867-5309/Jenny' |accessdate= June 28, 2017}}</ref> Not all numbers beginning with 555 are fictional. For example, 555-1212 is the standard number for [[directory assistance]]. Only 555-0100 through 555-0199 are reserved for fictional use. Where used, these are often routed to information services; Canadian telephone companies briefly promoted 555-1313 as a pay-per-use "name that number" reverse lookup in the mid-1990s.<ref>{{cite news|title=Canadian telco offers users a handy reverse directory.|publisher=America's Network|date=May 15, 1996}}</ref> ==See also== *[[Area codes in the Caribbean]] *[[List of North American Numbering Plan area codes]] *[[List of area code overlays]] *[[List of country calling codes]] *[[North American Numbering Plan expansion]] *[[Numbering Resource Utilization/Forecast Report]] ==References== {{Reflist|2}} ==External links== *[http://www.nationalnanpa.com North American Numbering Plan Administrator (NANPA)] *[http://www.cnac.ca/ Canadian Numbering Administrator] *[http://www.lincmad.com/map1947.html Map of the original 86 area codes from 1947] *[http://www.nanc-chair.org/ North American Numbering Council] *[https://web.archive.org/web/20111111184829/http://www.porticus.org/bell/doc/NANP_Discussion_2003R3.doc NANP Discussion 2003 Document - ''Understanding the North American Numbering Plan''] {{Telecommunications}} {{Americas topic|Telephone numbers in}} {{Area code list}} {{Continent topic |name = Telephone numbers by continent |title = Telephone numbers by continent |prefix = Telephone numbers in_ }} [[Category:North American Numbering Plan| ]] [[Category:Telephone numbers]] [[Category:Telecommunications-related introductions in 1947]]'