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.
Area codes 850 and 448 are telephone area codes in the North American Numbering Plan for the Florida Panhandle, including Pensacola, Tallahassee and Panama City. Area code 850 was created in 1997 in a split from 904, and area code 448 was assigned as a second code to the same area in an overlay plan in 2019, and mandatory ten-digit local calling began in May 2021.
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.
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.
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 208 and 986 are telephone area codes in the North American Numbering Plan for all of Idaho. Area code 208 is one of the 86 original area codes created by the American Telephone and Telegraph Company in 1947. It was Idaho's sole area code until 2017, when 986 was added as a second area code to the same numbering plan area by creating an overlay complex.
Area codes 801 and 385 are telephone area codes in the North American Numbering Plan (NANP) serving Salt Lake City and the four surrounding counties of the Wasatch Front in north-central Utah. The numbering plan area comprises Davis, Morgan, Salt Lake, Utah, and Weber counties. Other major towns and cities within the area are Alta, American Fork, Bountiful, Layton, Lehi, Murray, Ogden, Orem, Provo, Sandy, South Jordan, Spanish Fork, Taylorsville, West Jordan, and West Valley City. This numbering plan area is located in the Mountain Time Zone. Area code 801 is one of the original North American area codes created in 1947. Area code 385 was assigned to the same numbering plan area in 2008, creating an overlay complex.
Area codes 540 and 826 are telephone area codes in the North American Numbering Plan (NANP) for the north-western region of the U.S. State of Virginia, including the Shenandoah Valley, the Roanoke metropolitan area, the northern and eastern parts in Virginia of the New River Valley, and the outermost parts of the Washington metropolitan area. The Virginia State Corporation Commission authorized the addition of 826 to the numbering plan area for implementation in May 2022.
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 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 codes 973 and 862 are telephone area codes in the North American Numbering Plan (NANP) in the northernmost part of the U.S. state of New Jersey. The numbering plan area (NPA) comprises the counties, or parts, of Bergen, Essex, Hudson, Morris, Passaic, Sussex and Union Counties. Cities in this service area include Newark, Paterson, Clifton, Passaic, Montclair, Morristown, Parsippany, Dover, Maplewood, and The Oranges.
Area code 878 is an area code in the North American Numbering Plan for Southwestern Pennsylvania, centered in Pittsburgh. It forms an overlay complex with two distinct numbering plan areas, 412 in Pittsburgh and some suburban areas and 724 in surrounding 412 in the southwestern corner of the state. Area code 878 was activated on August 17, 2001.
Area codes 860 and 959 are telephone area codes in the North American Numbering Plan in the U.S. state of Connecticut. They are arranged in an overlay plan that covers most of the state, except its southwest, which uses area codes 203 and 475.
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.
