Area codes 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
Area code 202 was one of the original North American area codes established in October 1947 by AT&T. After the State of New Jersey with area code 201, the District of Columbia was the second numbering plan area (NPA). Area code 771 was added as a second area code to the numbering plan area in April 2021 to create an all-services overlay complex.
Since the creation of the North American Numbering Plan (NANP) in 1947, most of the inner ring of the Washington metropolitan area has been a single local calling area, the Washington Metropolitan Exchange Area (WMEA). This is despite the fact that the WMEA was split between three numbering plan areas (NPAs): the District's 202, 301 in southern Maryland, and 703 in Northern Virginia. From the 1950s to 1990, it was possible to complete local calls in the WMEA with only seven digits. The entire WMEA was reachable via long-distance services by dialing area code 202, for which purpose AT&T Long Lines had established cross-referenced operator routing codes for all affected central offices. This scheme was implemented via a system of central office code protection, in which central offices in the three numbering plan areas could not duplicate any central office prefixes for any of the three area codes in the WMEA. [1] If a 1-202-574 number was in use in the District, the corresponding 1-703-574 number or 1-301-574 number could only be assigned to jurisdictions a safe distance from the metropolitan area, such as southwestern Virginia or the Eastern Shore of Maryland. Conversely, if a 1-703-552 number was in use in Northern Virginia or a 1-301-552 Maryland suburbs, the corresponding 1-202-552 number could not be used in the District.
By Spring 1990, C&P Telephone (later part of Bell Atlantic and now Verizon), the Regional Bell Operating Company for the District, advised the North American Numbering Plan Administrator (NANPA) that the last interchangeable central office code in the area would be assigned in the second half of the year. The only remaining prefixes could not be assigned without breaking seven-digit dialing in the region, leading C&P to terminate the central office code protection scheme in order to make additional prefixes available for use. This change was implemented in a permissive dialing period from April 1, 1990, to October 1, 1990, at which time all home-NPA (HNPA) local calls maintained seven-digit dialing; all HNPA direct-dialed toll calls, required 1 and ten digits; foreign-NPA (FNPA) local calls were dialed with just the ten-digit number; FNPA direct dialed calls required dialing 1 and ten digits. Operator-assisted calls were all dialed as 0 and ten digits. [2]
The end of central office code protection was intended to allow numbers to be assigned in the Washington area that could not previously be assigned under the previous system. However, it did not provide enough relief to meet demand on either side of the Potomac River. By the end of 1990, the Chesapeake and Potomac Telephone Company of Maryland realized that 301 was on the brink of exhaustion even with the end of the central office code protection scheme. It filed to assign area code 410 to most of Maryland from the Baltimore area eastward, effective October 5, 1991. [3] In Virginia, the delay amounted to six years, until 1996, when area code 540 was installed for the western portion of the old 703 territory; permissive dialing ended January 27, 1996. [4]
The region's continued growth in the 1990s ultimately led to both suburban area codes being overlaid, with area code 240 overlaying 301 in 1997, and area code 571 overlaying 703 in 2000.
Years after the introduction of mobile number portability, many cell phone customers on the Virginia and Maryland sides of the metro have 202 numbers.[ citation needed ]
With 202 facing exhaustion in late 2022, the North American Numbering Plan Administrator announced in October 2020 that area code 771 would be added to the numbering plan area of the District of Columbia. The Public Service Commission of the District of Columbia approved a plan to phase in the new area code over a 13-month period. [5] 202 had been one of the few urbanized area codes without an overlay, making Washington one of the largest cities where seven-digit dialing was still possible. [6] The installation of a second area code broke seven-digit dialing for calls within the District. [7] The overlay implementation commenced with a permissive dialing period from April 10, 2021, to October 9, 2021, during which ten-digit dialing of 202-telephone numbers was optional. [8] [5] The first central office code assignments for 771 took place on November 8, 2021, for central office code 777, [9] and on November 9 for 888. [10]
Even with the implementation of ten-digit dialing in the Washington metro, much of the Washington area is a toll-free calling zone, [11] one of the largest in the eastern United States, covering large portions of Virginia and Maryland.
Areas such as Alexandria, Arlington, [12] Fairfax, [13] Falls Church, McLean and Tysons in Virginia [14] (703/571) and Rockville, [15] Gaithersburg, [16] Upper Marlboro, [17] Bethesda [18] and Landover in Maryland [19] (301/240) are a local call to Washington.
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.
Area codes 314 and 557 are telephone area codes in the North American Numbering Plan (NANP) in the U.S. state of Missouri, serving the city of St. Louis and most of its inner-ring suburbs in neighboring St. Louis County. The numbering plan area is bordered to the west by area code 636, which serves St. Louis' outer suburbs to the west, south, and north. Across the Mississippi River to the east, 314 is adjacent to area code 618, which serves southern Illinois and most of Metro East. Area code 557 was added to the 314 numbering plan area on August 12, 2022, to form an overlay numbering plan.
In telecommunications, an area code overlay complex is a telephone numbering plan that assigns multiple area codes to a 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.
Ten-digit dialing is a telephone dialing procedure in the countries and territories that are members of the North American Numbering Plan (NANP). It is the practice of including the area code of a telephone number when dialing to initiate a telephone call. When necessary, the ten-digit number may be prefixed with the trunk code 1, which is referred to as 1+10-digit dialing or national format.
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.
Area codes 920 and 274 are telephone area codes in the North American Numbering Plan (NANP) for a large area of eastern Wisconsin. Area code 920 was created on July 26, 1997, in a split of area code 414, one of the original North American area codes of 1947. 274 was added to the same numbering plan area (NPA) on May 5, 2023 to create an area code overlay.
Area code 564 is a telephone overlay area code in the North American Numbering Plan (NANP) for Western Washington state, including metropolitan Seattle. The area code was first proposed in 1999 to relieve telephone number shortages in area code 360, but implementation was delayed until 2017, when it was installed for an overlay complex that comprises only the numbering plan area 360. Neighboring area codes 206, 253, and 425 were slated for expansion of the overlay upon exhaustion of central office codes in each NPA. In 2023, area code 206 was approved for expansion with a guide line for preparation of inclusion of at least nine months. Ten-digit dialing has been mandatory in all of western Washington since July 29, 2017.
Area code 404 is a telephone area code in the North American Numbering Plan (NANP) for Atlanta, Georgia and its closest suburbs. This comprises roughly the area encircled by Interstate 285. It is an enclave area code, surrounded by area code 770, which serves most of Atlanta's suburbs. Both 404 and 770 are overlaid by area codes 678, 470, and 943.
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 876 and 658 are telephone area codes in the North American Numbering Plan (NANP) for Jamaica.
Area code 403 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Alberta. The numbering plan area encompasses the southern third of the province, which includes the Calgary area. This numbering plan area is also served by area codes 587, 825, and 368, which form a complex overlay for all of Alberta.
Area codes 678, 470, and 943 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. State of Georgia in the Atlanta metropolitan area. The area codes are assigned in an overlay plan to a combined numbering plan area (NPA) consisting of 404 and 770.
Area codes 610, 484, and 835 are telephone area codes in the North American Numbering Plan (NANP) for the eastern and southeastern regions of Pennsylvania. The numbering plan area (NPA) includes regions to the west of Philadelphia and the cities Allentown, Bethlehem, and Reading. It includes much of the Delaware Valley, including almost all of Delaware County, most of the Philadelphia Main Line, and all of the Lehigh Valley.
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 codes 303, 720 and 983 are telephone area codes in the North American Numbering Plan for the north-central portion of the U.S. state of Colorado. The numbering plan area comprises Denver and Boulder, as well as their surrounding suburbs, including Lakewood, Littleton, Longmont, Broomfield, Aurora, and Castle Rock. Area code 303 is the original area code, while area codes 720 and 983 were added to form an overlay complex for the area, meaning that the same geographic service area is served by all area codes and that ten-digit dialing is required for all calls made within the service area.
Area codes 816 and 975 are telephone area codes in the North American Numbering Plan (NANP) for most of the Missouri side of the Kansas City metropolitan area, the St. Joseph area, and all or part of 15 surrounding counties in northwestern Missouri. The numbering plan area originally comprised most of the northern and western two-thirds of the state, bordering with Arkansas, Illinois, Iowa, Kansas, Nebraska, and Oklahoma, but has been reduced to a ribbon bordering Kansas. 816 is one of the original 86 area codes created in 1947. The numbering plan area was converted to an overlay complex with area code 975 in 2023.
Area codes 703 and 571 are telephone area codes in the North American Numbering Plan (NANP) for Northern Virginia, including the independent cities of Alexandria, Fairfax, Falls Church, Manassas, and Manassas Park, as well as all of Arlington and Fairfax counties and parts of Fauquier, Loudoun, and Prince William counties. Area code 703 was created as one of the eighty-six original North American area codes in October 1947, and originally served the entire Commonwealth of Virginia. Area code 571 was created on March 1, 2000, to form an overlay plan with 703. The headquarters for The Chesapeake and Potomac Telephone Company of Virginia was at 703 East Grace Street, Richmond, Virginia.
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.
| North: 227/240/301 | ||
| West: 571/703 | 202/771 | East: 227/240/301 |
| South: 571/703 | ||
| Maryland area codes: 227/240/301, 410/443/667 | ||
| Virginia area codes: 276, 434, 540, 571/703, 686/804, 757/948 | ||