State California | ||
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Cities Walnut Creek, Concord, Pleasanton, Liver, San Ramon | ||
Area code 925 is a California telephone area code that was split from area code 510 on March 14, 1998. It covers the inland portions of the East Bay counties of Alameda and Contra Costa in the central area of California.
The area was originally part of area code 415, one of the first three area codes created in California in 1947, which originally covered all of central California. In 1991, area code 510 was created to encompass most of the East Bay. Area code 925 was created March 14, 1998, when area code 510 was split along the natural border of the East Bay hills. The number was formed by adding 415 and 510.
The area code 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).