The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the telephone country code 1. Some North American countries, most notably Mexico, do not participate with the NANP.
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.
Area codes 201 and 551 are telephone area codes in the North American Numbering Plan (NANP) in the U.S. State of New Jersey. Area code 201 was the area code assigned to the entire state of New Jersey in 1947, when the North American area code system was formed. After splits in 1956, 1991, and 1997, it is assigned to the northeastern portion of the state, including most of Hudson and Bergen counties, bordering New York City. Major cities in the numbering plan area include Bayonne, Jersey City, Hoboken, Hackensack, Secaucus and Englewood. Area code 551 was added to this numbering plan area in 2001 in formation of an overlay. Area code 201 is also assigned for wireless services in some rate centers in the 973 and 908 numbering plan areas, such as Newark, Morristown, and New Brunswick.
In telecommunications, an area code overlay complex is a telephone numbering plan that assigns multiple area codes to the same geographic numbering plan area (NPA). Area code overlays are implemented in territories of the North American Numbering Plan (NANP) to mitigate exhaustion of central office codes in growth areas. The method has been in use since 1992, and has been the exclusive method of area code relief since 2007.
Seven-digit dialing is a telephone dialing procedure customary in some territories of the North American Numbering Plan (NANP) for dialing telephone numbers in the same numbering plan area (NPA). NANP telephone numbers consist of ten digits, of which the leading three are the area code. In seven-digit dialing it is not necessary to dial the area code. The procedure is also sometimes known as local format or network format.
Telephone number pooling, thousands-block number pooling, or just number pooling, is a method of allocating telephony numbering space of the North American Numbering Plan in the United States. The method allocates telephone numbers in blocks of 1,000 consecutive numbers of a given central office code to telephony service providers. In the United States it replaced the practice of allocating all 10,000 numbers of a central office prefix at a time. Under number pooling, the entire prefix is assigned to a rate center, to be shared among all providers delivering services in that rate center. Number pooling reduced the quantity of unused telephone numbers in markets which have been fragmented between multiple service providers, avoided central office prefix exhaustion in high growth areas, and extended the lifetime of the North American telephone numbering plan without structure changes of telephone numbers. Telephone number pooling was first tested for area code 847 in Illinois in June 1998, and became national policy in a series of Federal Communications Commission (FCC) orders from 2000 to 2003.
Area codes 804 and 686 are telephone area codes in the North American Numbering Plan (NANP) for the east-central portion of Virginia. The numbering plan area is anchored by Virginia's capital, Richmond, and includes most of its metropolitan area. Other communities included are Chesterfield, Henrico, Hopewell, Mechanicsville, Powhatan, Midlothian, Petersburg, and Colonial Heights. This also includes the Northern Neck and the Middle Peninsula. The two southernmost counties on the Middle Peninsula, Gloucester and Mathews, are part of the Hampton Roads metropolitan area, but use 804 and 686 instead of the area codes 757 and 948 used by the rest of Hampton Roads.
Area codes 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
Area codes 757 and 948 are telephone area codes in the North American Numbering Plan (NANP) for the southeast corner of Virginia. Area code 757 was established July 1, 1996 in an area code split of area code 804. Area code 948 was established on February 5, 2020 forming an overlay complex with 757.
Area codes 540 and 826 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. State of Virginia. Areas included are the outer portions of Northern Virginia/D.C Area along with areas in or around the Shenandoah Valley, Blue Ridge Mountains, New River Valley, and the Roanoke metropolitan area. The Virginia State Corporation Commission authorized the addition of 826 to the numbering plan area for implementation in May 2022.
Area code 250 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of British Columbia outside the Lower Mainland, including Vancouver Island–home to the provincial capital, Victoria–and the province's Interior region. In addition, the numbering plan area extends into the United States community of Hyder, Alaska, located along the Canada–United States border near the town of Stewart. The incumbent local exchange carriers that service the area code are Telus, Northwestel, and CityWest in the city of Prince Rupert.
Area codes 717 and 223 are telephone area codes in the North American Numbering Plan (NANP) for South Central Pennsylvania and the Susquehanna Valley. The numbering plan area (NPA) includes the Harrisburg, Lancaster, and York metropolitan areas and a considerable portion of Pennsylvania Dutch Country, an area with nearly two million people.
Area code 604 is a telephone area code in the North American Numbering Plan for southwestern British Columbia, Canada. The numbering plan area comprises the Metro Vancouver, Sunshine Coast, Howe Sound / Sea to Sky Corridor, Fraser Valley and the lower Fraser Canyon regions. The major city is Vancouver. The area code is one of the nine original North American area codes assigned to Canada in 1947.
Area codes 408 and 669 are telephone area codes in the North American Numbering Plan (NANP) in the U.S. state of California. The numbering plan area comprises most of Santa Clara County and Northern Santa Cruz County, and includes Gilroy, Morgan Hill, Saratoga, Los Gatos, Monte Sereno, Milpitas, Sunnyvale, Santa Clara, Cupertino, Campbell, and San Jose.
Area codes 304 and 681 are telephone area codes in the North American Numbering Plan (NANP) for the entirety of the U.S. state of West Virginia. The numbering plan area was established in October 1947 with area code 304, as one of the eighty-six original North American area codes. Area code 681 was added to the same area in an overlay plan that took effect on March 28, 2009.
Area codes 301, 240, and 227 are telephone area codes in the North American Numbering Plan (NANP) for the western part of the U.S. state of Maryland. The numbering plan area (NPA) comprises Maryland's portion of the Greater Washington, D.C. metro area, portions of southern Maryland, along with rural western Maryland. This includes the communities of Cumberland, Frederick, Hagerstown, Gaithersburg, Potomac, Germantown, Bethesda, Rockville, Landover, Silver Spring, and Waldorf.
Area codes 410, 443, and 667 are telephone area codes in the North American Numbering Plan (NANP) for the eastern half of the U.S. state of Maryland. The numbering plan area (NPA) includes the Baltimore metropolitan area and the Eastern Shore. The three area codes are overlay codes for one numbering plan area, among which 410 was the initial area code for the NPA, when it was split from area code 301 in 1991. 443 and 667 found assignment primarily in cellular service and for competitive local exchange carriers, such as Comcast and Cavalier Telephone, when introduced, but have since become universal in carrier availability.
Area code 360 is a telephone area code in the North American Numbering Plan (NANP) for western Washington state outside metropolitan Seattle and west of the Cascade Mountains. Its numbering plan area (NPA) comprises all of western Washington outside urban King, Pierce, and Snohomish counties and Bainbridge Island, Until January 15, 1995, when the area code commenced service, the numbering plan area (NPA) was served by area code 206, Washington's original area code since 1947.
Area codes 513 and 283 are telephone area codes in the North American Numbering Plan (NANP) for the southwest of the U.S. state of Ohio, including Cincinnati and surrounding cities, such as Forest Park, Hamilton, Lebanon, West Chester, Mason, Maineville, Middletown, Milford, Norwood, Oxford, Harrison, Cleves, Miamitown and Trenton.
In the administration of the North American Numbering Plan, central office code protection is a numbering policy for maintaining local seven-digit dialing in communities that extend on both sides of the boundary line between multiple numbering plan areas (NPAs), such as in cross-border towns on state lines. Code protection prevents the use of the same telephone number on both sides by not assigning the same central office code of one NPA in the adjacent NPA.
