The 831 area code covers Salinas, Santa Cruz and 19 more places in California.
Area code 831 is in California, on Pacific Time. In the 831 area, phone numbers are given out most in Monterey County, then Santa Cruz and San Benito counties. It has been in service since July 11, 1998.
- Where
- Monterey County, Santa Cruz County and San Benito County, California
- Time zone
- Pacific Time
- In service since
- July 11, 1998
- Shares its area with
- No other area code
- Prefixes in use
- 406
- How to dial
- Local calls inside 831 can still be dialed with just 7 digits.
Find out who called you from an 831 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (831) number is on today, use our free carrier lookup.
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Salinas holds 21% of the phone prefixes in area code 831.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 406 prefixes in use shows where 831 numbers are actually given out.
- Salinas84 prefixes, 21%
- Santa Cruz76 prefixes, 19%
- Monterey64 prefixes, 16%
- Watsonville30 prefixes, 7%
- Hollister22 prefixes, 5%
- Aptos19 prefixes, 5%
- Carmel12 prefixes, 3%
- Ben Lomond11 prefixes, 3%
Also served: Felton, Boulder Creek, Soledad and Greenfield and 9 smaller places.
Pacific Bell (AT&T) holds the most phone number prefixes in area code 831: 124 of 406.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 406 prefixes in use in 831 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| Pacific Bell (AT&T)AT&T's landline company | 124 | 31% |
| AT&T MobilityMobile network | 35 | 9% |
| Level 3 (Lumen)Lumen's business and wholesale network | 29 | 7% |
| IP Horizon | 14 | 3% |
| Metro by T-MobileT-Mobile's prepaid brand | 13 | 3% |
| T-MobileMobile network | 13 | 3% |
| 35 other carriers | 178 | 44% |
76% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
831 has covered the same ground since 1998.
1998
831 starts on July 11, 1998, split off from 408.
An 831 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.
The area codes closest to 831 are 408, 650 and 510.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
California has 40 other area codes.
These are the questions people ask most about area code 831.
Where is area code 831?
831 covers Salinas, Santa Cruz, Monterey and Watsonville and 17 more places in California. In the 831 area, phone numbers are given out most in Monterey County, then Santa Cruz and San Benito counties.
What state is area code 831 in?
California. 831 is a California area code on Pacific Time.
What cities use area code 831?
The places holding the most 831 prefixes are Salinas, Santa Cruz, Monterey, Watsonville, Hollister, Aptos, Carmel and Ben Lomond, out of 21 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 831?
No single phone company owns 831. NANPA's records show Pacific Bell (AT&T) holds the most 831 prefixes, 124 of 406, followed by AT&T Mobility and Level 3 (Lumen). Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 831 in?
831 is on Pacific Time.
When did area code 831 start?
831 went into service on July 11, 1998, when it was split off from 408.
How do I dial an 831 number?
Local calls inside 831 can still be dialed with just 7 digits.
Is 831 a toll-free number?
No. 831 is a regular area code for Salinas and Santa Cruz in California, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 831?
The closest are 408/669 (San Jose, California), 650 (Palo Alto, California), 510/341 (Oakland, California) and 925 (Walnut Creek, California), measured between the centres of each area.
Who called me from an 831 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 831 a scam?
831 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.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.