The 408 area code serves San Jose and Silicon Valley, California — the technology heartland of Santa Clara County. In service since 1959, 408 covers one of the most influential regions in the world for innovation and industry. If a 408 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 408 at a Glance
| Detail | Information |
|---|---|
| Area Code | 408 |
| State | California (CA) |
| Major Cities | San Jose, Santa Clara, Sunnyvale, Cupertino |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | 669 |
Geographic Coverage & Major Cities
Area code 408 covers most of Santa Clara County and a small part of San Benito County, at the southern end of the San Francisco Bay Area. It sits at the core of Silicon Valley and shares its territory with the 669 overlay.
Cities and communities served by the 408 area code include:
- San Jose — the Bay Area’s largest city and the capital of Silicon Valley
- Santa Clara and Sunnyvale — home to many major technology companies
- Cupertino — headquarters of Apple and other tech firms
- Milpitas, Campbell, Los Gatos, and Gilroy — surrounding Santa Clara Valley communities
Because it defines Silicon Valley, a 408 number carries strong associations with the technology industry, making it a recognizable business identifier.
A Brief History of Area Code 408
Area code 408 was created in 1959, split from the original 415 code to serve the southern Bay Area and the Central Coast. Over the decades its territory narrowed — the Monterey and Santa Cruz areas moved to 831 in 1998 — leaving 408 focused on Santa Clara County. To meet Silicon Valley’s demand for numbers, the 669 overlay was introduced in 2012 across the same territory, bringing mandatory 10-digit dialing to the region.
Time Zone & Best Time to Call
Numbers in the 408 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 408
Because of the 669 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 — 408-XXX-XXXX.
- 11-digit dialing: You can also dial 1-408-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 408 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 408 XXX XXXX
- From any mobile phone worldwide: +1 408 XXX XXXX
Is Area Code 408 a Scam? Safety & Protection Tips
Area code 408 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 Silicon Valley 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 |
|---|---|
| Tech-company impersonation | Fake “account security” or software-support pitches |
| Government impersonation | Callers posing as the IRS or SSA threatening arrest or fines |
| Job & recruitment scams | Fake tech-job offers requesting fees or personal information |
| Bank & card fraud alerts | Claims of “suspicious activity” seeking your account details |
How to report, block, and look up 408 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 408 sits among several other Bay Area codes:
- 669 — the overlay that shares Silicon Valley with 408
- 650 — the Peninsula to the north (see our 650 area code guide)
- 415 & 628 — San Francisco and Marin County (see our 415 area code guide)
- 510 & 341 (Oakland/East Bay) and 831 (Monterey/Santa Cruz)
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 408
Where is the 408 area code located?
Area code 408 covers San Jose and Silicon Valley in Santa Clara County, California, including Santa Clara, Sunnyvale, and Cupertino. It operates on Pacific Time and shares its territory with the 669 overlay.
Is 408 a landline or cell phone area code?
Both. Area code 408 serves landlines, mobile phones, and VoIP numbers throughout the Silicon Valley region.
Why is a 408 number popular with businesses?
408 is synonymous with Silicon Valley, so the code signals a genuine presence in the heart of the technology industry — especially valuable for tech firms and startups.
Should I answer a call from an unknown 408 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 408 Guides
- Is a 408 call safe? Read Is area code 408 a scam? Spam & safety guide.
- Local coverage: see the San Jose area code guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.