Where Is Area Code 925?
Area code 925 serves the inland East Bay of Northern California. It covers most of Contra Costa County and parts of eastern Alameda County within the San Francisco Bay Area. Antioch is the primary city associated with this area code.
Major communities include Concord, Walnut Creek, Pittsburg, Brentwood, Danville, San Ramon, Dublin, Pleasanton, and Livermore. The service area extends from the San Joaquin-Sacramento River Delta near Antioch and Oakley to the Tri-Valley communities in southern Alameda and Contra Costa counties.
Mount Diablo and Mount Diablo State Park are notable geographic features in the area. Other important sites include Lawrence Livermore National Laboratory in Livermore and Saint Mary's College of California in Moraga.
Cities and Communities in the 925 Area Code
- Antioch, Contra Costa County
- Brentwood, Contra Costa County
- Clayton, Contra Costa County
- Concord, Contra Costa County
- Danville, Contra Costa County
- Dublin, Alameda County
- Lafayette, Contra Costa County
- Livermore, Alameda County
- Martinez, Contra Costa County
- Moraga, Contra Costa County
- Oakley, Contra Costa County
- Orinda, Contra Costa County
- Pittsburg, Contra Costa County
- Pleasant Hill, Contra Costa County
- Pleasanton, Alameda County
- San Ramon, Contra Costa County
- Walnut Creek, Contra Costa County
History of Area Code 925
Area code 925 went into service on March 14, 1998, after a split from area code 510. The new area code covered most of Contra Costa County and eastern parts of Alameda County, while area code 510 continued to serve the western East Bay.
Area code 341 became an overlay for the 925 region on March 22, 2019. An overlay adds a second area code to the same geographic territory instead of requiring existing customers to change numbers. The overlay provided additional telephone numbers as residential and business demand increased across the East Bay.
Key Facts About Area Code 925
- Area code 925 is a geographic area code in California.
- Antioch is the primary city associated with area code 925.
- Area code 925 covers portions of Contra Costa County and Alameda County.
- Area code 925 is in the U.S. Census Pacific region and uses Pacific Time.
- Area code 925 went into service on March 14, 1998, after a split from area code 510.
- Area code 341 has overlaid the 925 geographic region since March 22, 2019.
- Mount Diablo State Park is located within the area code 925 service region.
- Lawrence Livermore National Laboratory is located in Livermore, a city within the 925 region.
Frequently Asked Questions
What state is area code 925 in?
Area code 925 is in California.
What major cities use area code 925?
Major cities using area code 925 include Antioch, Concord, Walnut Creek, Pittsburg, Brentwood, Danville, San Ramon, Dublin, Livermore, and Pleasanton.
What time zone is area code 925 in?
Area code 925 uses Pacific Time.
Is area code 925 a toll-free number?
No, area code 925 is a geographic area code, not a toll-free number.