Area code 925 is a telephone

area code A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...

in the

North American Numbering Plan The North American Numbering Plan (NANP) is an integrated 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, World Numbering Zone ...

for a northern part of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. It was created in an

area code split In telecommunications, an area code split is the practice of introducing a new telephone area code by geographically dividing an existing numbering plan area (NPA), and assigning area codes to the resulting divisions, but retaining the existing a ...

of area code 510 in 1998. The numbering plan area comprises the inland portions of the East Bay counties of Alameda and Contra Costa.

History

The numbering plan area (NPA) was originally served with area code 415, one of the first three area codes of California in 1947, which originally was assigned to central California. In 1991, area code 510 was created to serve most of the

East Bay The East Bay is the eastern region of the San Francisco Bay Area and includes cities along the eastern shores of San Francisco Bay and San Pablo Bay. The region has grown to include inland communities in Alameda and Contra Costa counties. Wi ...

. Area code 925 was created March 14, 1998, when area code 510 was split along the natural border of the

Berkeley Hills The Berkeley Hills are a range of the Pacific Coast Ranges, and overlook the northeast side of the valley that encompasses San Francisco Bay. They were previously called the "Contra Costa Range/Hills" (from the original Spanish ''Sierra de la Co ...

. Prior to October 2021, area code 925 had telephone numbers assigned for the

central office code The North American Numbering Plan (NANP) is an integrated telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Numbering Zone 1 and has the ...

988. In 2020, ''988'' was designated nationwide as a dialing code for the

National Suicide Prevention Lifeline The Suicide and Crisis Lifeline in the United States, or Suicide Crisis Helpline in Canada, and formerly known as the National Suicide Prevention Lifeline, is a suicide prevention and crisis help line to a network of a large number of crisis ce ...

, which created a conflict for exchanges that permit

seven-digit dialing Seven-digit dialing is a telephone dialing procedure customary in some territories of the North American Numbering Plan (NANP) for dialing telephone numbers in the same numbering plan area (NPA). NANP telephone numbers consist of ten digits, of wh ...

. The area code was therefore transitioned to

ten-digit dialing Ten-digit dialing is a telephone dialing procedure in the countries and territories of the North American Numbering Plan (NANP). It is the practice of including the area code of a telephone number when Dialling (telephony), dialing to initiate a t ...

on October 24, 2021.

Service area

The numbering plan area includes southeastern Alameda County (Dublin, Pleasanton, Livermore, Sunol, and unincorporated areas surrounding those communities), and all of Contra Costa County except the western part (El Cerrito to Crockett).

Alameda County

* Altamont * Dougherty *

Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...

* East Pleasanton * Kilkare Woods * Livermore * Pleasanton * San Ramon Village * Sunol * Ulmar

Contra Costa County

Alamo The Battle of the Alamo (February 23 – March 6, 1836) was a pivotal event and military engagement in the Texas Revolution. Following a 13-day siege, Mexican troops under President General Antonio López de Santa Anna reclaimed the Alam ...

* Alamo Oaks *

Antioch Antioch on the Orontes (; , ) "Antioch on Daphne"; or "Antioch the Great"; ; ; ; ; ; ; . was a Hellenistic Greek city founded by Seleucus I Nicator in 300 BC. One of the most important Greek cities of the Hellenistic period, it served as ...

* Bay Point * Bethel Island * Bixler * Blackhawk * Brentwood *

Byron George Gordon Byron, 6th Baron Byron (22 January 1788 – 19 April 1824) was an English poet. He is one of the major figures of the Romantic movement, and is regarded as being among the greatest poets of the United Kingdom. Among his best-kno ...

* Camino Tassajara *

Canyon A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency t ...

* Clayton * Clyde * Concord * Contra Costa Centre * Danville * Diablo *

Discovery Bay Discovery Bay is a picturesque residential community located on Lantau Island. The 2021 census recorded a population of 19,336 residents in DB, with 55% of them being non-Chinese. DB is home to a significant community compared of expatriates ...

* Knightsen * Lafayette * Marsh Creek Springs * Martinez * Mococo * Moraga * Norris Canyon * Oakley * Orinda * Orwood * Pacheco * Pittsburg * Pleasant Hill * San Ramon * Saranap * Shore Acres * Vine Hill * Walnut Creek

References

External links

Report on the 925 area code
produced by the

California Public Utilities Commission The California Public Utilities Commission (CPUC or PUC) is a regulatory agency that regulates privately owned public utilities in the state of California, including electric power, telecommunications, natural gas and water companies. In addition ...

, Telecommunications Division {{coord, 37.9, -122, region:US-CA, display=title

925 Year 925 ( CMXXV) was a common year starting on Saturday of the Julian calendar. Events By date January – June * January 5 – Gabellus becomes the first abbot of the monsastery of San Martín de Albelda in the Spanish kingdom ...

Alameda County, California Contra Costa County, California

Northern California