The 840 area code covers the same area as 909, including Ontario, San Bernardino and 21 more places in California.
840 has been in service since 2021, on Pacific Time. 909 covers the same area, so two neighbours can have different area codes.
- Where
- 4 counties in California, mostly San Bernardino County, Los Angeles County and Riverside County
- Time zone
- Pacific Time
- In service since
- 2021
- Shares its area with
- 909 (since 1992)
- Prefixes in use
- 126
- How to dial
- Local calls need 1, then the area code, then the number: 1-840-555-0142.
Find out who called you from an 840 number.
Enter the full 10-digit number to see who it is listed to, where it is registered, and whether it is a mobile, landline or VoIP line.
Pomona holds 13% of the phone prefixes in area code 840.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 126 prefixes in use shows where 840 numbers are actually given out.
- Pomona16 prefixes, 13%
- San Bernardino14 prefixes, 11%
- Fontana12 prefixes, 10%
- Chino8 prefixes, 6%
- Claremont8 prefixes, 6%
- Ontario7 prefixes, 6%
- Upland7 prefixes, 6%
- Colton6 prefixes, 5%
Also served: Redlands, Rialto, Diamond Bar and Highland and 11 smaller places.
840 started in 2021 as an overlay on 909, and its ground has not changed since.
2021
840 starts as an overlay on 909: new numbers on the same ground.
An 840 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
California has 40 other area codes.
These are the questions people ask most about area code 840.
Where is area code 840?
840 covers Ontario, San Bernardino, Fontana and Upland and 19 more places in California, in San Bernardino County, Los Angeles County and Riverside County.
What time zone is area code 840 in?
840 is on Pacific Time.
Is 840 the same area as 909?
Yes. 909 (since 1992) covers the same ground as 840. Nobody's number changed when it was added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.
How do I dial an 840 number?
Local calls need 1, then the area code, then the number: 1-840-555-0142.
Who called me from an 840 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 840 a scam?
840 is a real California area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.