Area code 831: where it is and who calls from it
Area code 831 is in California.
California (Monterey County, including Salinas and Monterey); San Benito County (including Hollister); and Santa Cruz County (including Santa Cruz and Watsonville)
| Where | California |
|---|---|
| Time zone | Pacific Time ยท local time |
| In service since | 1998 |
| Overlay | No |
| Prefixes assigned | 406 of 792 possible (51%) |
Where 831 numbers started
Every prefix is assigned to a rate center, the local calling area it was set up in. These are the biggest in 831, with how many prefixes each has.
Who holds 831 numbers
- Mobile carrier 23%
- Local phone company 31%
- Internet / business phone carrier 42%
- Phone company 4%
| Carrier | Type | Prefixes | Share |
|---|---|---|---|
| AT&T (local phone) | Local phone company | 126 | 31% |
| AT&T Mobility | Mobile carrier | 35 | 9% |
| Onvoy | Internet / business phone carrier | 35 | 9% |
| Verizon Wireless | Mobile carrier | 30 | 7% |
| Level 3 (Lumen) | Internet / business phone carrier | 29 | 7% |
| IP Horizon | Internet / business phone carrier | 14 | 3% |
| T-Mobile (including Sprint) | Mobile carrier | 13 | 3% |
| MetroPCS (T-Mobile) | Mobile carrier | 13 | 3% |
| MCImetro (Verizon Business) | Internet / business phone carrier | 11 | 3% |
| Tpx Communications | Internet / business phone carrier | 11 | 3% |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number.
States served: California.
Other area codes in California
209 213 279 310 323 341 350 357 369 408 415 424 442 510 530 559 562 619 626 628 650 657 661 669 707 714 738 747 760 805 818 820 837 840 858 909 916 925 949 951
Got a call from 831?
An area code tells you where a number was first assigned, not where the caller is. People keep their numbers when they move, and scammers can fake any number. If you weren't expecting the call, let it go to voicemail.
If the call shows a 831 number that matches the first six digits of your own, that's often neighbor spoofing. Use the box above to check the full number.
Area code facts from the NANPA area code database (updated 10/06/2026); prefixes and carriers from NANPA's central office code records (updated 2026-10-10). Place description adapted from Wikipedia, CC BY-SA 4.0.