# Area code 925 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Area_code_925 > Markdown URL: https://mediated.wiki/source/Area_code_925.md > Source: https://en.wikipedia.org/wiki/Area_code_925 > Source revision: 1340737849 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Area code in California, United States}} {{Use mdy dates|date=February 2026}} {{Use American English|date=February 2026}} {{California area codes image map|925}} '''Area code 925''' is a telephone [area code](/source/area_code) in the [North American Numbering Plan](/source/North_American_Numbering_Plan) for a northern part of the [U.S. state](/source/U.S._state) of [California](/source/California). It was created in an [area code split](/source/area_code_split) of [area code 510](/source/area_code_510) in 1998. The numbering plan area comprises the inland portions of the East Bay counties of [Alameda](/source/Alameda_County%2C_California) and [Contra Costa](/source/Contra_Costa_County%2C_California). ==History== The numbering plan area (NPA) was originally served with [area code 415](/source/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](/source/area_code_510) was created to serve most of the [East Bay](/source/East_Bay_(San_Francisco_Bay_Area)). Area code 925 was created March 14, 1998, when area code 510 was split along the natural border of the [Berkeley Hills](/source/Berkeley_Hills). Prior to October 2021, area code 925 had telephone numbers assigned for the [central office code](/source/central_office_code) 988. In 2020, ''988'' was designated nationwide as a dialing code for the [National Suicide Prevention Lifeline](/source/National_Suicide_Prevention_Lifeline), which created a conflict for exchanges that permit [seven-digit dialing](/source/seven-digit_dialing). The area code was therefore transitioned to [ten-digit dialing](/source/ten-digit_dialing) on October 24, 2021.{{cite web |url=https://www.nanpa.com/sites/default/files/planning_letters/PL-556.pdf |title=Planning Letter 556: Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Hotline) |publisher=NANPA |date=2021-01-08 |access-date=2025-04-01 }} ==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=== {{div col|colwidth=20em}} *[Altamont](/source/Altamont%2C_California) *[Dougherty](/source/Dougherty%2C_Alameda_County%2C_California) *[Dublin](/source/Dublin%2C_California) *[East Pleasanton](/source/East_Pleasanton%2C_California) *[Kilkare Woods](/source/Kilkare_Woods%2C_California) *[Livermore](/source/Livermore%2C_California) *[Pleasanton](/source/Pleasanton%2C_California) *[San Ramon Village](/source/San_Ramon_Village%2C_California) *[Sunol](/source/Sunol%2C_California) *[Ulmar](/source/Ulmar%2C_California) {{div col end}} ===Contra Costa County=== {{div col|colwidth=20em}} *[Alamo](/source/Alamo%2C_California) *[Alamo Oaks](/source/Alamo_Oaks%2C_California) *[Antioch](/source/Antioch%2C_California) *[Bay Point](/source/Bay_Point%2C_California) *[Bethel Island](/source/Bethel_Island%2C_California) *[Bixler](/source/Bixler%2C_California) *[Blackhawk](/source/Blackhawk%2C_California) *[Brentwood](/source/Brentwood%2C_California) *[Byron](/source/Byron%2C_California) *[Camino Tassajara](/source/Camino_Tassajara%2C_California) *[Canyon](/source/Canyon%2C_California) *[Clayton](/source/Clayton%2C_California) *[Clyde](/source/Clyde%2C_California) *[Concord](/source/Concord%2C_California) *[Contra Costa Centre](/source/Contra_Costa_Centre%2C_California) *[Danville](/source/Danville%2C_California) *[Diablo](/source/Diablo%2C_California) *[Discovery Bay](/source/Discovery_Bay%2C_California) *[Knightsen](/source/Knightsen%2C_California) *[Lafayette](/source/Lafayette%2C_California) *[Marsh Creek Springs](/source/Marsh_Creek_Springs%2C_California) *[Martinez](/source/Martinez%2C_California) *[Mococo](/source/Mococo%2C_California) *[Moraga](/source/Moraga%2C_California) *[Norris Canyon](/source/Norris_Canyon%2C_California) *[Oakley](/source/Oakley%2C_California) *[Orinda](/source/Orinda%2C_California) *[Orwood](/source/Orwood%2C_California) *[Pacheco](/source/Pacheco%2C_California) *[Pittsburg](/source/Pittsburg%2C_California) *[Pleasant Hill](/source/Pleasant_Hill%2C_California) *[San Ramon](/source/San_Ramon%2C_California) *[Saranap](/source/Saranap%2C_California) *[Shore Acres](/source/Shore_Acres%2C_California) *[Vine Hill](/source/Vine_Hill%2C_California) *[Walnut Creek](/source/Walnut_Creek%2C_California) {{div col end}} ==See also== *[List of California area codes](/source/List_of_California_area_codes) ==References== {{Reflist}} ==External links== {{Area_code_footer|Map=CA}} *[http://docs.cpuc.ca.gov/Published/Graphics/7344.PDF Report on the 925 area code] produced by the [California Public Utilities Commission](/source/California_Public_Utilities_Commission), Telecommunications Division {{Area code box | State = CA | This = 925 | N = [707/369](/source/area_codes_707_and_369), [916/279](/source/area_codes_916_and_279) | S = [408/669](/source/area_codes_408_and_669) | E = [209/350](/source/area_codes_209_and_350) | W = [510/341](/source/area_codes_510_and_341) }} {{coord|37.9|-122|region:US-CA|display=title}} 925 Category:Alameda County, California Category:Contra Costa County, California 925 Category:Northern California --- Adapted from the Wikipedia article [Area code 925](https://en.wikipedia.org/wiki/Area_code_925) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Area_code_925?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.