The 925 area code serves the inland East Bay of the San Francisco Bay Area, California, including Concord, Walnut Creek, and the Tri-Valley cities. Created in 1998, 925 covers Contra Costa County and eastern Alameda County, the suburban communities east of the Oakland–Berkeley hills. If a 925 number has appeared on your caller ID, this guide explains where it comes from, how to dial it, and how to stay safe from spoofed calls.
Quick Summary: Area Code 925 at a Glance
| Detail | Information |
|---|---|
| Area Code | 925 |
| State | California (CA) |
| Major Cities | Concord, Walnut Creek, Antioch, Pleasanton |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | None (single area code) |
Geographic Coverage & Major Cities
Area code 925 covers most of Contra Costa County and the eastern (Tri-Valley) portion of Alameda County, the inland suburbs of the East Bay. It sits east of the hills that separate it from Oakland and Berkeley.
Cities and communities served by the 925 area code include:
- Concord and Walnut Creek — central Contra Costa’s commercial hubs
- Antioch, Pittsburg, and Brentwood — the growing East County communities
- Pleasanton, Livermore, and Dublin — the Tri-Valley in eastern Alameda County
- Danville and San Ramon — the San Ramon Valley suburbs
Because it covers these established inland suburbs, a 925 number carries a recognizable East Bay identity valued by residents and businesses.
A Brief History of Area Code 925
Area code 925 was created in 1998, split from 510 as the East Bay outgrew a single code. The split kept 510 for the inner East Bay (Oakland, Berkeley, Fremont) and assigned 925 to the inland Contra Costa and Tri-Valley communities. To date, 925 has remained a single area code without an overlay, though 10-digit dialing is now standard across California.
Time Zone & Best Time to Call
Numbers in the 925 area code use Pacific Time (PT). The region observes Daylight Saving Time, shifting from PST (UTC−8) to PDT (UTC−7) between March and November each year.
How to Dial Phone Numbers in Area Code 925
Ten-digit dialing is now standard throughout California, so always include the area code.
Calling within the United States or Canada
- 10-digit dialing: Dial the full number — 925-XXX-XXXX.
- 11-digit dialing: You can also dial 1-925-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 925 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 925 XXX XXXX
- From any mobile phone worldwide: +1 925 XXX XXXX
Is Area Code 925 a Scam? Safety & Protection Tips
Area code 925 is a legitimate California area code — a call from it is not fraudulent by default. However, scammers frequently spoof the code, faking the caller ID so their number appears to come from a trusted local East Bay line. Neighbor spoofing, which mimics your own number’s first six digits, is especially common in suburban areas.
Common scam tactics linked to this region
| Scam type | What to watch for |
|---|---|
| Government impersonation | Callers posing as the IRS or SSA threatening arrest or fines |
| Utility shut-off threats | Demands for immediate payment to avoid disconnection |
| Bank & card fraud alerts | Claims of “suspicious activity” seeking your account details |
| Home-services scams | Fake calls about “required” repairs, warranties, or inspections |
How to report, block, and look up 925 callers
- Never share personal or financial details with an unexpected caller, however urgent they sound.
- Block the number using your phone’s built-in call-blocking feature or a reputable call-screening app.
- Look up the number with a trusted reverse phone lookup before returning any call.
- Report it to the FTC at reportfraud.ftc.gov and register at DoNotCall.gov.
Nearby & Related Area Codes in California
Area code 925 borders several other Bay Area codes:
- 510 & 341 — the inner East Bay to the west (see our 510 area code guide)
- 415 & 628 — San Francisco (see our 415 area code guide)
- 408 & 669 — San Jose and Silicon Valley to the south
- 209 — the northern San Joaquin Valley (Stockton, Tracy) to the east
Explore more codes across the state on our California area codes hub, or browse every prefix in our US area codes directory.
↑ See the complete list of All US Area Codes by State – every area code across all 50 states in one directory.
Explore Neighboring States
Researching area codes just across the state line? Start with these codes in the states that border California:
Frequently Asked Questions About Area Code 925
Where is the 925 area code located?
Area code 925 covers the inland East Bay of the San Francisco Bay Area, including Concord, Walnut Creek, Antioch, and the Tri-Valley cities of Pleasanton, Livermore, and Dublin. It operates on Pacific Time.
Is 925 a landline or cell phone area code?
Both. Area code 925 serves landlines, mobile phones, and VoIP numbers throughout Contra Costa County and the Tri-Valley.
Does 925 have an overlay area code?
No. 925 remains a single area code without an overlay, though 10-digit dialing is now standard statewide.
Should I answer a call from an unknown 925 number?
If you are not expecting the call, let it go to voicemail. Legitimate callers leave a message, while spoofed or robocall numbers usually will not. Verify any unfamiliar number with a reverse lookup before calling back.
Related 925 Guides
- Is a 925 call safe? Read Is area code 925 a scam? Spam & safety guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.