The 510 area code serves the East Bay region of the San Francisco Bay Area, California, including Oakland, Berkeley, and Fremont. In service since 1991, 510 covers Alameda County and western Contra Costa County along the eastern shore of San Francisco Bay. If a 510 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 510 at a Glance
| Detail | Information |
|---|---|
| Area Code | 510 |
| State | California (CA) |
| Major Cities | Oakland, Berkeley, Fremont, Hayward |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | 341 |
Geographic Coverage & Major Cities
Area code 510 covers most of Alameda County and the western part of Contra Costa County, running along the East Bay shoreline across from San Francisco. It shares its territory with the 341 overlay.
Cities and communities served by the 510 area code include:
- Oakland — the East Bay’s largest city and a major port and cultural center
- Berkeley — home to the University of California, Berkeley
- Fremont and Hayward — populous southern Alameda County cities
- Richmond, Alameda, and San Leandro — bayside communities
Because it covers the diverse, densely populated East Bay, a 510 number carries a distinctive Bay Area identity valued by residents and businesses.
A Brief History of Area Code 510
Area code 510 was created in 1991, split from 415 to serve the East Bay as the Bay Area’s demand for numbers grew. In 1998, the inland eastern communities were moved to the new 925 code, leaving 510 focused on the inner East Bay. To add capacity, the 341 overlay was introduced in 2019 across the same territory, bringing mandatory 10-digit dialing to the region.
Time Zone & Best Time to Call
Numbers in the 510 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 510
Because of the 341 overlay, the region requires 10-digit dialing on every call.
Calling within the United States or Canada
- 10-digit dialing: Always include the area code — 510-XXX-XXXX.
- 11-digit dialing: You can also dial 1-510-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 510 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 510 XXX XXXX
- From any mobile phone worldwide: +1 510 XXX XXXX
Is Area Code 510 a Scam? Safety & Protection Tips
Area code 510 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.
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 |
| Student & tuition scams | Calls about “unpaid tuition” targeting university communities |
How to report, block, and look up 510 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 510 sits among several other Bay Area codes:
- 341 — the overlay that shares the East Bay with 510
- 925 — the inland East Bay (Contra Costa) to the east (see our 925 area code guide)
- 415 & 628 — San Francisco across the bay (see our 415 area code guide)
- 650 (the Peninsula) and 408 (San Jose/Silicon Valley — see our 650 area code guide)
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 510
Where is the 510 area code located?
Area code 510 covers the East Bay of the San Francisco Bay Area, including Oakland, Berkeley, Fremont, and Hayward. It operates on Pacific Time and shares its territory with the 341 overlay.
Is 510 a landline or cell phone area code?
Both. Area code 510 serves landlines, mobile phones, and VoIP numbers throughout the East Bay.
What is the difference between 510 and 925?
510 covers the inner East Bay (Oakland, Berkeley, Fremont), while 925 covers the inland East Bay (Concord, Walnut Creek, Pleasanton). The two split in 1998.
Should I answer a call from an unknown 510 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 510 Guides
- Is a 510 call safe? Read Is area code 510 a scam? Spam & safety guide.
- Local coverage: see the Oakland area code guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.