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Area code 770 is a telephone area code in the North American Numbering Plan (NANP) serving all or part of 29 counties in North Georgia, including most of Atlanta's suburbs. It was created in 1995 in a split of numbering plan area (NPA) 404.
When the North American Numbering Plan was created in October 1947, all of Georgia was served by area code 404. In 1954, 404 was reduced to the northern half of the state, with Macon and points south splitting off as area code 912. The remaining 404 territory remained unchanged until 1992, when most of the area outside of the immediate Atlanta metropolitan area was split off with area code 706. This was intended as a long-term solution to relieve number shortages in exchanges in North Georgia.
When 706 was created, it included several fast-growing exurbs of Atlanta. Residents of these areas complained about no longer being associated with the better-known area code 404, prompting BellSouth to return these areas to 404 soon after the split. However, even before the creation of 706, 404 was close to exhaustion due to the proliferation of cell phones, fax machines, and pagers in the fast-growing Atlanta area. BellSouth and the Georgia Public Service Commission were well aware of this, and had already planned to create a new area code for the Atlanta suburbs later in the decade. However, the restoration of the exurban areas from 706 forced further relief action sooner than anticipated.
As a result, just three years later, in 1995, almost all of Atlanta's suburban ring was split off as area code 770. 
Atlanta was the first city in the United States to have mandatory ten-digit dialing throughout its metro area, roughly coinciding with the 1996 Summer Olympics in Atlanta. Atlanta was used as the test case not only for its size, but also because it enjoyed the world's largest fiber optic bundle at the time (five times that of New York), and it was home to BellSouth (now part of AT&T), then the Southeastern Regional Bell Operating Company.
An additional NPA will be added to both metro Atlanta overlay areas in 2022. Area code 943 will be effective on March 15, 2022. 
Numbering plan area 770 completely surrounds 404. The two plan areas are separated roughly by Interstate 285, known locally as the Perimeter. Generally, 770 includes most of the metro area outside the Perimeter, while 404 serves Atlanta itself and most suburbs inside the Perimeter; a few cities are split between the two codes. Both codes are overlaid by 678 and 470. The metro Atlanta region (404, 770, 678, 470 and parts of 706/762) is a local calling area, and no long-distance charges are applied for calls from one portion of the metro to the other.
Cell phone subscribers in the region can choose from either the 770 or 470 area code when signing up for service.[ citation needed ] When the area was originally divided in 1995, most cellphones stayed with 404, which balanced the fact that most of the landline area went to 770.
Area code 770 serves a numbering plan area that comprises the counties of Barrow, Bartow, Butts, Carroll, Cherokee, Clayton (part with area code 404), Cobb, Coweta, Dawson, DeKalb (part with area code 404), Douglas, Fayette, Forsyth, Fulton (part with area code 404), Gwinnett, Hall, Haralson, Heard (part with area codes 706 and 762), Henry, Lamar, Meriwether (part with area codes 706 and 762), Newton, Oconee, Paulding, Pike, Polk, Rockdale, Spalding, and Walton.
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 international calling code 1. Some North American countries, most notably Mexico, do not participate in the NANP.
Interstate 285 (I-285) is an Interstate Highway loop encircling Atlanta, Georgia, for 63.98 miles (102.97 km). It connects the three major interstate highways to Atlanta: I-20, I-75 and I-85. Colloquially referred to as The Perimeter, it also carries unsigned State Route 407 (SR 407), and is signed as Atlanta Bypass on I-20, I-75, and I-85.
Area codes 508 and 774 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. state of Massachusetts. The numbering plan area comprises south-central and most of southeastern Massachusetts. It includes Worcester, Outer south and southwest Greater Boston, as well as Fall River, New Bedford, Cape Cod, Martha's Vineyard, and Nantucket.
Area code 612 is a telephone area code in the North American Numbering Plan (NANP) in the U.S. state of Minnesota. The numbering plan area comprises the city of Minneapolis and a few surrounding municipalities such as Fort Snelling, St. Anthony, and Richfield. Geographically, it is the smallest area code in the state of Minnesota. The area code is one of the two original area codes in the 1947 nationwide numbering plan for the state, when it was assigned to a much larger area, including the entire Twin Cities region and a wide area surrounding it.
Area code 952 is the telephone area code in the North American Numbering Plan (NANP) for the southwestern suburbs of Minneapolis-St. Paul in the U.S. state of Minnesota. The numbering plan area (NPA) includes cities such as Bloomington, Eden Prairie, Edina and Minnetonka. It was created in 2000 along with area code 763 when they were carved out of area code 612, which now only contains Minneapolis and a few inner-ring locales.
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 and 470.
Area codes 706 and 762 are telephone area codes in the North American Numbering Plan (NANP) for the northern and west central parts of Georgia, but excluding metropolitan Atlanta.
Area codes 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
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 778, 236, and 672 are area codes in the North American Numbering Plan (NANP) for the entire Canadian province of British Columbia. They form an overlay complex with area code 604, which serves only a small southwestern section, the Lower Mainland, of the province, and area code 250, which serves the rest of the province.
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 215, 267, and 445 are the North American telephone area codes for the City of Philadelphia as well as adjacent portions of Bucks and Montgomery counties in the Commonwealth of Pennsylvania. The original area code is 215, which was established in 1947, while 267 and 445 are overlay codes for the same numbering plan area (NPA).
Area codes 301 and 240 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, Bethesda, Rockville, Landover, Silver Spring, and Waldorf.
Area code 334 is a telephone area code in the North American Numbering Plan (NANP) for southeastern Alabama. It was created on January 15, 1995, as a split from area code 205. Up until the time of the split, 205 had been Alabama's sole area code since the implementation of area codes in 1947.
Area codes 609 and 640 are telephone area codes in the North American Numbering Plan (NANP) for the central part of the U.S. state of New Jersey. The numbering plan area includes the cities of Trenton, Princeton, Ewing, Hamilton, and southeastern parts of the state and the Jersey Shore, including Atlantic City and Long Beach Island. In terms of geographic coverage, it is the largest numbering plan area in New Jersey.
Area codes 803 and 839 are telephone area codes in the North American Numbering Plan (NANP) for the central part of the U.S. State of South Carolina. The numbering plan area (NPA) is anchored by the city of Columbia, the state capital. It also includes most of the South Carolina portions of the Charlotte, North Carolina and Augusta, Georgia metropolitan areas. 839, an all-service overlay, was approved by the South Carolina Public Service Commission in 2019.
Area code 912 is a telephone area code in the North American Numbering Plan (NANP) for the southeastern part of the U.S. state of Georgia. The numbering plan area contains Savannah, Richmond Hill, Hinesville, Vidalia, Metter, Reidsville, Homerville, Waycross, Brunswick, Folkston, Douglas, Statesboro, Ludowici, Jesup and Kingsland. The area code was created in 1954 in an area code split from area code 404, which had been assigned to the entire state in 1947.
Perimeter Center is a major edge city in metro Atlanta, Georgia, United States. It is centered on Perimeter Mall, the nucleus around which it has formed. Perimeter Center is located north of Atlanta proper, and lies within three cities: Dunwoody, Sandy Springs, and Brookhaven. It is one of metro Atlanta's largest business districts, and one of the largest edge cities in the United States, comprising over 29 million square feet (2,700,000 m2) of office space, 6 million square feet (560,000 m2) of retail space, and 40,000 residents.
Metro Atlanta, designated by the United States Office of Management and Budget as the Atlanta–Sandy Springs–Alpharetta, GA Metropolitan Statistical Area, is the most populous metro area in the US state of Georgia and the eighth-largest metropolitan statistical area (MSA) in the United States. Its economic, cultural and demographic center is Atlanta, and has a total population of 6,144,050 according to the 2021 ACS estimate from the US Census Bureau. The metro area forms the core of a broader trading area, the Atlanta–Athens-Clarke–Sandy Springs Combined Statistical Area. The Combined Statistical Area spans up to 39 counties in north Georgia and has a total 2020 census population of 6,930,423. Atlanta is considered a "beta(+) world city." It is the second-largest metropolitan region in the Census Bureau's Southeast region behind Greater Washington. It surpassed the Greater Miami area in 2021.
|West: 256/938||area code 770 completely surrounds 404; entire region overlaid by 470 and 678||East: 706/762|
|South: 478, 706/762|
|Alabama area codes: 205/659, 251, 256/938, 334|
Coordinates: 34°02′19″N84°20′35″W / 34.03853°N 84.34311°W