Area code 831 is a telephone area code in the North American Numbering Plan for a small region of the U.S. state of California. The numbering plan area (NPA) comprises Monterey County, San Benito County, and Santa Cruz County. The area code was created in 1998 in an area code split of area code 408.
In 1947, the American Telephone and Telegraph Company (AT&T) devised the first nationwide telephone numbering plan and assigned the original North American area codes. The state of California was divided into three numbering plan areas (NPAs) with distinct area codes: 213, 415, and 916, for the southern, central, and northern parts of the state, respectively. [1] California area codes were reorganized geographically in 1950, so that 916 was assigned to a numbering plan area that comprised only the northeastern part from the Sierra Nevada to the Central Valley. The coastal area to the west was assigned area code 415. [2]
Area code 408 was split from numbering plan area 415 on March 1, 1959. The new numbering plan area included most of Santa Clara, Santa Cruz, Monterey and San Benito Counties.
In 1997, the California/Nevada Code Administrator (C/NCA) advised the North American Numbering Plan Administration (NANPA) of the need for area code relief in the 408 numbering plan area. A geographic area code split had been approved by the California Public Utilities Commission (CPUC) which would install area code 831 for a new numbering plan area comprising the communities of Santa Cruz, Salinas, Monterey, and Hollister. Area code 408 would be retained in Sunnyvale, San Jose, Los Gatos, and Gilroy. The area code split became effictive on July 11, 1998, with a permissive dialing period ending on February 20, 1999. [3]
Due to the relatively small size of the area (in both area and population), exhaustion of 831 is unlikely for the foreseeable future. [4]
The service area of NPA 831 includes Big Sur, Monterey Bay, the Salinas Valley, and the southwestern Santa Cruz Mountains.
Major cities in the area are Salinas, Hollister, Monterey, Santa Cruz and places in the northern Central Coast. [5]
Monterey County, officially the County of Monterey, is a county located on the Pacific coast in the U.S. state of California. As of the 2020 census, its population was 439,035. The county's largest city and county seat is Salinas.
Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles, accessible via CA 1 and US 101.
The Central Coast is an area of California, roughly spanning the coastal region between Point Mugu and Monterey Bay. It lies northwest of Los Angeles and south of the San Francisco Bay Area, and includes the rugged, rural, and sparsely populated stretch of coastline known as Big Sur.
Area codes 213 and 323 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. state of California. They are assigned in an overlay complex to a numbering plan area (NPA) that comprises, roughly, the area of downtown Los Angeles City, as well as several southeast Los Angeles County cities, such as Bell and Huntington Park. Area code 213 was one of the original North American area codes of 1947 and 323 was created in an area code split of 213 in 1998. This was the fifth split of 213 and left it serving only downtown Los Angeles and immediately adjoining neighborhoods. In 2017, the two NPAs were recombined in the overlay.
Area codes 916 and 279 are California telephone area codes that serve Sacramento, the state capital, and most of its suburbs. Area code 916 was one of the first three original area codes established in California in October 1947. It originally covered most of northeastern California, but area code splits have reduced its coverage to the greater Sacramento area. Area code 279 began service in March 2018 to relieve an exhausted supply of telephone numbers in the 916 area code.
Area codes 415 and 628 are telephone area codes in the North American Numbering Plan (NANP) for the city of San Francisco and its northern suburbs in Marin County, and the northeast corner of San Mateo County in the U.S. state of California. Area code 415 was one of the eighty-six original North American area codes established in 1947, but modified in geographic configuration later. Area code 628 was assigned in 2015 to form an overlay in that numbering plan area in mitigation of central office prefix exhaustion.
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.
Area codes 714 and 657 are telephone area codes in the North American Numbering Plan for the southern part of the U.S. state of California. The numbering plan area comprises northern Orange County, a portion of Los Angeles County, and the Sleepy Hollow and Carbon Canyon areas of Chino Hills in San Bernardino County. Area code 714 was assigned to a part of numbering plan area 213 in 1951, and 657 was added in 2008 to form an overlay complex.
Area codes 909 and 840 are telephone area codes in the North American Numbering Plan for the far-eastern part of Los Angeles County and southwestern San Bernardino 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.
Area codes 619 and 858 are telephone area codes in the North American Numbering Plan (NANP) for most of San Diego County in the U.S. state of California. Area code 619 was created by a split of area code 714 in 1982. In 1999, a part of the 619 numbering plan area was assigned area code 858 in northwest San Diego County. In 2019, the area code boundary between 619 and 858 was eliminated, creating an overlay complex with the two area codes.
Area code 559 is a telephone area code in the North American Numbering Plan for the central San Joaquin Valley in central California. The numbering plan area includes the counties of Fresno, Madera, Kings, and Tulare, an area largely coextensive with the Fresno and Visalia-Porterville metropolitan areas. The area code was placed in service in 1998, when its services area was split from that of area code 209.
Area code 951 is a telephone area code in the North American Numbering Plan for western Riverside County in the southern part of the U.S. state of California. It was assigned in 2004 to a new numbering plan area that was created by an area code split of area code 909.
Area codes 209 and 350 are telephone area codes in the North American Numbering Plan (NANP) for the U.S. state of California. Their service area includes Stockton, Modesto, Turlock, Merced, Winton, Atwater, Livingston, Manteca, Ripon, Tracy, Lodi, Galt, Sonora, Los Banos, San Andreas, Mariposa, and Yosemite, the northern San Joaquin Valley, and the Sierra Foothills.
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 510 and 341 are telephone area codes in the North American Numbering Plan (NANP) serving much of the East Bay in the U.S. state of California. They cover parts of Contra Costa County and western Alameda County, including the city of Oakland, but excluding Dublin, Livermore, Pleasanton, and Sunol.
Area code 530 is a telephone area code in the North American Numbering Plan (NANP) in northeastern and Northern California. It was created in 1997 in an area code split of 916.
Area codes 707 and 369 are telephone area codes in the North American Numbering Plan (NANP) for the northwestern part of the U.S. state of California. The area codes serve part of the northern San Francisco Bay Area, as well as the North Coast. Major cities in the area codes include Napa, Sebastopol, Vallejo, Benicia, Fairfield, Santa Rosa, Windsor, Healdsburg, Rohnert Park, Petaluma, Fort Bragg, Rio Vista, Crescent City, Eureka, Clearlake, Vacaville, Dixon, and Ukiah. 707 was created by a split of area code 415 on March 1, 1959. Area code 369 was added to the numbering plan area (NPA) on February 1, 2023, to form an overlay numbering plan in the service area.
Area code 956 is a telephone area code in the North American Numbering Plan for the Lower and Middle Rio Grande Valley regions in the U.S. state of Texas. The numbering plan area includes the communities of Brownsville, McAllen, Laredo and South Padre Island. The area code was created May 25, 1997, in a split from area code 210.
The Association of Monterey Bay Area Governments (AMBAG) is a regional governmental organization which consists of representation of a large number of public agencies within Monterey County, Santa Cruz County and San Benito County, California. AMBAG has a broad charter of research and governmental oversight for a variety of functions including elements of land planning, natural resource conservation, energy, transportation, and economic development. The following governmental entities are members of AMBAG:
| North: 408/669, 650 | ||
| West: Pacific Ocean, 808 | 831 | East: 209/350, 559 |
| South: 805/820 | ||
| Hawaii area codes: 808 | ||