North American area code 510 is a California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 telephone

Telephone

The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 area code which covers most eastern Bay Area cities in Alameda County (including the city of Oakland

Oakland, California

Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

 but excluding Dublin

Dublin, California

Dublin is a suburban city of the East Bay region of Alameda County, California, United States. Located along the north side of Interstate 580 at the intersection with Interstate 680, roughly east of Hayward, west of Livermore and north of San Jose, it was named after the city of Dublin in...

, Livermore

Livermore, California

Livermore is a city in Alameda County. The population as of 2010 was 80,968. Livermore is located on the eastern edge of California's San Francisco Bay Area....

, Pleasanton

Pleasanton, California

Pleasanton is a city in Alameda County, California, incorporated in 1894. It is a suburb in the San Francisco Bay Area located about east of Oakland, and west of Livermore. The population was 70,285 at the 2010 census. In 2005 and 2007, Pleasanton was ranked the wealthiest middle-sized city in...

, and Sunol

Sunol, California

Sunol is an unincorporated census-designated place in Alameda County, California, United States. The population was 913 at the 2010 census....

), and western Contra Costa County. The area code was created from a split of area code 415

Area code 415

North American Area code 415 is the Californian telephone area code for San Francisco and its northern suburbs .-History:415 was one of the original three area codes in California, established in 1947...

 on September 2, 1991.

Area code 925

Area code 925

In the North American Numbering Plan , area code 925 is an area code that covers the inland portions of the East Bay counties of Alameda and Contra Costa in northern California....

 was created on March 14, 1998 from the eastern portion of the then 510 area code. The East Bay Hills serve as the rough dividing line.

Alameda County

Alameda County, California

Alameda County is a county in the U.S. state of California. It occupies most of the East Bay region of the San Francisco Bay Area. As of the 2010 census it had a population of 1,510,271, making it the 7th most populous county in the state...

• Alameda
  Alameda, California
  Alameda is a city in Alameda County, California, United States. It is located on Alameda Island and Bay Farm Island, and is adjacent to Oakland in the San Francisco Bay. The Bay Farm Island portion of the city is adjacent to the Oakland International Airport. At the 2010 census, the city had a...
  
  
• Albany
  Albany, California
  Albany is a city in Alameda County, California, United States. The population was 18,539 at the 2010 census.-History:In 1908, a group of local women protested the dumping of Berkeley garbage in their community...
  
  
• Ashland
  Ashland, California
  Ashland is a census-designated place in Alameda County, California, United States. The population was 21,925 at the 2010 census.-Geography:...
  
  
• Berkeley
  Berkeley, California
  Berkeley is a city on the east shore of the San Francisco Bay in Northern California, United States. Its neighbors to the south are the cities of Oakland and Emeryville. To the north is the city of Albany and the unincorporated community of Kensington...
  
  
• Castro Valley
  Castro Valley, California
  Castro Valley is a census-designated place in Alameda County, California, United States. As of the 2000 census, it is the fifth most populous unincorporated area in California, and the twenty-third in the United States...
  
  
• Cherryland
  Cherryland, California
  Cherryland is a census-designated place in Alameda County, California, United States.The unincorporated community is located between the cities of San Leandro to the north and Hayward to the south...
  
  
• Emeryville
  Emeryville, California
  Emeryville is a small city located in Alameda County, California, in the United States. It is located in a corridor between the cities of Berkeley and Oakland, extending to the shore of San Francisco Bay. Its proximity to San Francisco, the Bay Bridge, the University of California, Berkeley, and...
  
  
• Fairview
  Fairview, California
  Fairview is a census-designated place in Alameda County, California, United States. It borders on the city of Hayward. The population was 10,003 at the 2010 census.-Geography:...
  
  
• Farwell
  Farwell, California
  Farwell is an unincorporated community in Alameda County, California. It is located north-northeast of downtown Fremont, at an elevation of 213 feet . Its ZIP code is 94536 and its area code is 510.The name is in honor of James Dumaresy Farwell, land owner....
  
  
• Fremont
  Fremont, California
  Fremont is a city in Alameda County, California. It was incorporated on January 23, 1956, from the merger of five smaller communities: Centerville, Niles, Irvington, Mission San Jose, and Warm Springs...
  
  
• Hayward
  Hayward, California
  Hayward is a city located in the East Bay in Alameda County, California. With a population of 144,186, Hayward is the sixth largest city in the San Francisco Bay Area and the third largest in Alameda County. Hayward was ranked as the 37th most populous municipality in California. It is included in...
  
  
• Newark
  Newark, California
  Newark is a city in Alameda County, California, United States. It was incorporated as a city in September 1955. Newark is an enclave, completely surrounded by the city of Fremont. Its population was 42,573 at the 2010 census.-Geography:...
  
  
• Oakland
  Oakland, California
  Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...
  
  
• Piedmont
  Piedmont, California
  Piedmont is a small, affluent city in Alameda County, California, United States. It is surrounded by the city of Oakland. The population was 10,667 at the 2010 census. Piedmont was incorporated in 1907 and was developed significantly in the 1920s and 1930s...
  
  
• San Leandro
  San Leandro, California
  San Leandro is a city in Alameda County, California, United States. It is considered a suburb of Oakland and San Francisco. The population was 84,950 as of 2010 census. The climate of the city is mild throughout the year.-Geography and water resources:...
  
  
• San Lorenzo
  San Lorenzo, California
  San Lorenzo , also known as San Lorenzo Village is a census-designated place in Alameda County, California, United States. The population was 23,452 at the 2010 census.-Geography:...
  
  
• Union City
  Union City, California
  Union City is a city in Alameda County, California, United States. It was incorporated in 1959, combining the communities of Alvarado and Decoto. Alvarado was the original county seat of Alameda County, and the site of the first county courthouse is a California Historical Landmark . The city...
  
  

Contra Costa County

Contra Costa County, California

Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, it had a population of 1,049,025...

• Bayview-Montalvin
  Bayview-Montalvin, California
  Bayview-Montalvin is a former census-designated place in Contra Costa County, California, United States. The population was 5,004 at the 2000 census.Prior to the 2010 census, the CDP was dissolved into Bayview CDP and Montalvin Manor CDP.-Geography:...
  
  
• Canyon
  Canyon, California
  Canyon is an unincorporated community in Contra Costa County, California situated between Oakland and Moraga in the San Francisco Bay Area. The community is named for its location in the upper canyon of San Leandro Creek along the eastern slope of the Berkeley Hills...
  
  
• Crockett
  Crockett, California
  Crockett is a census-designated place in Contra Costa County, California, United States. The population was 3,094 at the 2010 census...
  
  
• East Richmond Heights
  East Richmond Heights, California
  East Richmond Heights is an unincorporated and census-designated place in western Contra Costa County, California, United States. The community is locally referred to as Richmond View or Arlington Heights, especially in the context of real estate advertisements...
  
  
• Eastport
  Eastport, California
  Eastport is a small unincorporated community in Contra Costa County, California, United States. It is located south of Orinda, at an elevation of 830 feet . It lays along Pinehurst Road between Oakland and Canyon, which is the closest settlement. The ZIP Code is 94516. The community is inside area...
  
  
• El Cerrito
  El Cerrito, Contra Costa County, California
  -Transportation:The city's primary transportation infrastructure consists of the El Cerrito Plaza and El Cerrito del Norte BART stations along with several local bus lines, operated by AC Transit, providing access to the surrounding area and the nearby cities of Albany, Berkeley and Richmond...
  
  
• El Sobrante
  El Sobrante, California
  El Sobrante is a census-designated place in Contra Costa County, California, United States. The population was 12,669 at the 2010 census...
  
  
• Hercules
  Hercules, California
  Hercules is a city in western Contra Costa County, California. Situated along the coast of San Pablo Bay, it is located in the eastern region of the San Francisco Bay Area, about northeast of San Francisco. The city has a 2010 population of 24,060 according to the U.S...
  
  
• Kensington
  Kensington, California
  Kensington is an unincorporated community and census-designated place located in the East Bay, part of the San Francisco Bay Area, in Contra Costa County, California, United States. The population was 5,077 at the 2010 census.- Law and government :Kensington is an unincorporated area of Contra...
  
  
• Mountain View
  Mountain View, Contra Costa County, California
  Mountain View is a census-designated place in Contra Costa County, California, United States. The population was 2,372 at the 2010 census.-Geography:Mountain View is located at ....
  
  
• North Richmond
  North Richmond, California
  North Richmond is a community in Contra Costa County, California, a census-designated place of 3,717 adjacent to and nearly surrounded by the city Richmond, to which it is generally socially and culturally attached...
  
  
• Pinole
  Pinole, California
  Pinole is a city in Contra Costa County, California, United States. The population was 18,390 at the 2010 census. It is one of many small “bedroom communities” along the I-80 corridor in Western Contra Costa County. It is located about northeast of San Francisco, and approximately a half-hour...
  
  
• Port Costa
  Port Costa, California
  Port Costa is a census-designated place in Contra Costa County, California, United States. The population was 190 at the 2010 census.-Geography:...
  
  
• Richmond
  Richmond, California
  Richmond is a city in western Contra Costa County, California, United States. The city was incorporated on August 7, 1905. It is located in the East Bay, part of the San Francisco Bay Area. It is a residential inner suburb of San Francisco, as well as the site of heavy industry, which has been...
  
  
• Rodeo
  Rodeo, California
  Rodeo is a census-designated place located in Contra Costa County, California on the shore of San Pablo Bay. The population was 8,679 at the 2010 census. The town is named for the livestock roundups common in the late 19th century...
  
  
• Rollingwood
  Rollingwood, California
  Rollingwood is a census-designated place in Contra Costa County, California, United States. As of the 2010 census, Rollingwood's population was 2,969.-Geography:...
  
  
• San Pablo
  San Pablo, California
  San Pablo is a city in Contra Costa County, California, United States. The city of Richmond surrounds nearly the whole city. The population was 29,139 at the 2010 census. The current Mayor is Paul V. Morris, and the current Vice Mayor is Cecilia Valdez. Current Councilmembers include Arturo M....
  
  
• Tara Hills
  Tara Hills, California
  Tara Hills is a census-designated place in Contra Costa County, California, United States. The population was 5,126 at the 2010 census.-Geography:According to the United States Census Bureau, the CDP has a total area of , all of it land....
  
  
• Vine Hill
  Vine Hill, California
  Vine Hill is a census-designated place in Contra Costa County, California, United States. The population was 3,761 at the 2010 census. It is located east of downtown Martinez.-Geography:...
  
  

Prior usage for TWX

The 510 area code (along with area codes 610, 710, 810, and 910) was used prior to 1981 by AT&T

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

 for their TWX, or TeletypeWriter eXchange network. The area code was decomissioned for TWX usage in 1981 when Western Union

Western Union

The Western Union Company is a financial services and communications company based in the United States. Its North American headquarters is in Englewood, Colorado. Up until 2006, Western Union was the best-known U.S...

, who had acquired the TWX network in 1969 from AT&T and renamed it Telex II

Telex II

Telex II is the later name for the TWX teletypewriter network, which was originally founded & established by AT&T. It was later acquired from AT&T by Western Union, who renamed it Telex II....

, upgraded the network to "4-row" ASCII

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

 operation (it previously used both "3-row" Baudot

Baudot code

The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No 2 , the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, sent over a...

and ASCII transmission).

External links

• List of exchanges from AreaCodeDownload.com, 510 Area Code