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.
Area codes 805 and 820 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. state of California. The numbering plan area (NPA) includes most or all of the counties of San Luis Obispo, Santa Barbara, Ventura, and the southernmost portions of Monterey County. 805 was split from area code 213 in 1957, and area code 820 was added to the NPA in 2018, creating an area code overlay.
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.
Area codes 561 and 728 are telephone area codes in the North American Numbering Plan (NANP) for Palm Beach County in the U.S. state of Florida. 561 was created on May 13, 1996, in a split of area code 407. The numbering plan area (NPA) comprises nearly every major city in the county, the largest of which being West Palm Beach, Boca Raton, Wellington, Boynton Beach, Jupiter, Delray Beach, and Belle Glade. On March 10, 2023, area code 728 was added to the same numbering plan area to form an all-services distributed 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 codes 909 and 840 are telephone area codes in the North American Numbering Plan for the far-eastern part of Los Angeles County, southwestern San Bernardino County, and a small portion of Riverside County in the U.S. state of California. Area code 909 was created on November 14, 1992, in an area code split of 909, and 840 was added to the numbering plan area to form an overlay complex effective February 23, 2021. While most of western Riverside County now uses Area code 951, some residents in Eastvale and Corona were allowed to keep the 909 area code after the split in 2004.
Area codes 516 and 363 are telephone overlay area codes in the North American Numbering Plan (NANP) for the U.S. state of New York. The numbering plan area (NPA) comprises Nassau County on Long Island. Area code 516 was created in 1951, while area code 363 was added to the numbering plan area in 2023.
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 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
Area codes 813 and 656 are area codes in the North American Numbering Plan for the U.S. state of Florida in the city of Tampa, Florida, and its surrounding areas, such as Zephyrhills and Oldsmar. In 2022, due to exhaustion of central office prefixes, area code 656 was added to the service area forming 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 306, 639, and 474 are telephone area codes in the North American Numbering Plan (NANP) for the entire Canadian province of Saskatchewan. Area code 306 is one of the original North American area codes assigned in 1947. Area codes 639 and 474 were added to the numbering plan area in creation of an overlay complex for the entire province in 2013 and 2021, respectively. The incumbent local exchange carrier is SaskTel.
Area codes 704 and 980 are telephone area codes in the North American Numbering Plan (NANP) for Charlotte and all or part of 12 surrounding counties in south-central North Carolina. Other major cities in the service area are Gastonia, Kannapolis, Concord, Mooresville, Salisbury, Statesville, and Shelby. The South Carolina side of the Charlotte metropolitan area is part of area codes 803 and 839. Area code 704 is one of the original area codes assigned to numbering plan areas (NPAs) by AT&T in October 1947. Area code 980 was added in an overlay numbering plan in 2000.
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 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 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 code 970 is a telephone area code in the North American Numbering Plan (NANP) for most of the western and northern parts of the U.S. state of Colorado. The numbering plan area includes Aspen, Breckenridge, Durango, Estes Park, Fort Collins, Glenwood Springs, Grand Junction, Greeley, Loveland, Silverthorne, Steamboat Springs, and Vail. It was established on April 2, 1995 in an area code split of area code 303, which was retained by the Denver 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 870 and 327 are telephone area codes in the North American Numbering Plan (NANP) for southern, eastern, and most of northern Arkansas. 870 was created on April 14, 1997, in a split from area code 501, Arkansas's original area code of 1947, and 327 was added as part of an overlay complex in 2024.
