The 840 area code is an overlay serving the eastern Inland Empire of Southern California, layered over the 909 code across San Bernardino County. Introduced in 2018 to supply new phone numbers, 840 covers the exact same territory as 909. If an 840 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 840 at a Glance
| Detail | Information |
|---|---|
| Area Code | 840 |
| State | California (CA) |
| Major Cities | San Bernardino, Ontario, Rancho Cucamonga, Fontana |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | 909 (co-located) |
Geographic Coverage & Major Cities
Area code 840 covers the eastern Inland Empire, including the San Bernardino Valley and the eastern edge of Los Angeles County. Because it is an overlay, it shares the identical footprint of the 909 area code rather than covering a separate zone.
Cities and communities served by the 840 area code include:
- San Bernardino – the county seat and largest city in the region
- Ontario, Rancho Cucamonga & Fontana – major logistics and residential hubs
- Pomona, Chino & Chino Hills – communities on the Los Angeles County border
- Upland, Redlands & Rialto – established San Bernardino Valley cities
As a newer code over one of the fastest-growing regions in California, 840 numbers are typically assigned to residents and businesses who obtained phone service after the region’s original 909 numbers grew scarce.
A Brief History of Area Code 840
Area code 840 was activated in 2018 as an all-services overlay on the 909 region. The 909 code split from Orange County’s 714 in 1992, and later gave up western Riverside County to the new 951 code in 2004. An overlay adds a second area code across the same geographic area, so existing 909 customers kept their numbers while new lines could be assigned either 909 or 840. The area uses mandatory 10-digit dialing to keep every number unique.
Time Zone & Best Time to Call
Numbers in the 840 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 840
Because 840 is an overlay of 909, the region requires 10-digit dialing on every call.
Calling within the United States or Canada
- 10-digit dialing: Always include the area code – 840-XXX-XXXX.
- 11-digit dialing: You can also dial 1-840-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 840 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 840 XXX XXXX
- From any mobile phone worldwide: +1 840 XXX XXXX
Is Area Code 840 a Scam? Safety & Protection Tips
Area code 840 is a legitimate California area code – a call from it is not fraudulent by default. However, scammers frequently spoof local codes like 840, faking the caller ID so their number appears to come from a trusted Inland Empire line. Neighbor spoofing, which mimics the first six digits of your own number, 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 |
| Bank & card fraud alerts | Claims of “suspicious activity” seeking your account details |
| Utility shut-off threats | Demands for immediate payment to avoid disconnection |
| Package delivery scams | Fake texts or calls about a “failed delivery” with a bad link |
How to report, block, and look up 840 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 840 sits alongside several other Southern California codes:
- 909 – the original San Bernardino code that 840 overlays (see our 909 area code guide)
- 951 – western Riverside County, split from 909 in 2004 (see our 951 area code guide)
- 760 & 442 – the deserts and High Desert to the east (see our 760 area code guide)
- 626 – Pasadena and the San Gabriel Valley to the west (see our 626 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 840
Where is the 840 area code located?
Area code 840 covers the eastern Inland Empire of California, including San Bernardino, Ontario, Rancho Cucamonga, and Fontana. It operates on Pacific Time as an overlay of area code 909.
What is the difference between 840 and 909?
There is no geographic difference. 840 is an overlay covering the exact same area as 909; it was added simply to supply more phone numbers as the Inland Empire grew.
Is 840 a landline or cell phone area code?
Both. Area code 840 serves landlines, mobile phones, and VoIP numbers throughout the eastern Inland Empire.
Should I answer a call from an unknown 840 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 840 Guides
- Worried about spam or robocalls? Browse our Scam Alerts directory.