| District of California area codes: 925 | |
|---|---|
| Country | United States |
| State/Province | California |
| Major City | Oakland |
| Time Zone | Pacific |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 925-417 | Alameda | Pleasanton, CA | Pacific Bell |
| 925-418 | Contra Costa | Brentwood, CA | Broadwing Communications |
| 925-419 | Contra Costa | San Ramon, CA | American Messaging Services |
| 925-420 | Contra Costa | Brentwood, CA | O1 Communications |
| 925-421 | Contra Costa | Concord, CA | Bandwidth.com Clec |
| 925-422 | Alameda | Livermore, CA | Pacific Bell |
| 925-423 | Alameda | Livermore, CA | Pacific Bell |
| 925-424 | Alameda | Livermore, CA | Pacific Bell |
| 925-425 | Alameda | Pleasanton, CA | Teleport Communications Group - San Francisco |
| 925-426 | Alameda | Pleasanton, CA | Pacific Bell |
| 925-427 | Contra Costa | Pittsburg, CA | Pacific Bell |
| 925-428 | Contra Costa | Antioch, CA | T-mobile Usa |
| 925-429 | Contra Costa | Concord, CA | Broadwing Communications |
| 925-431 | Contra Costa | Pittsburg, CA | Pacific Bell |
| 925-432 | Contra Costa | Pittsburg, CA | Pacific Bell |
| 925-435 | Contra Costa | Concord, CA | T-mobile Usa |
| 925-437 | Contra Costa | Antioch, CA | New Cingular Wireless PCS |
| 925-438 | Contra Costa | Orinda, CA | U.s. Telepacific Corp. |
| 925-439 | Contra Costa | Pittsburg, CA | Pacific Bell |
| 925-443 | Alameda | Livermore, CA | Pacific Bell |
There are 552 prefixes, In the code area, the major cities are Antioch, CA;Bay Point, CA;Brentwood, CA;Concord, C. The major city is Oakland.