Area code
831
831 is a United States area code. Under the North American Numbering Plan it belongs to California, which has 41 area codes in total.
Validate a number in 831
Paste a full number and the tool checks it against the numbering plan. It returns the standard formats, the line type the plan assigns and the area code region.
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Area code 831 at a glance
NANPA lists 404 central office codes (prefixes) in use in area code 831, held by 44 holders across 24 rate centers.
| Fact | Value |
|---|---|
| In service since | 1998-07-11 |
| Time zone | Pacific (P) |
| Prefixes in use | 404 |
| Pooled prefixes | 306 (76%) |
| Rate centers | 24 |
| Companies holding prefixes | 44 |
| Assignment dates on file | 2001-03-09 to 2026-05-20 (118 prefixes) |
| ZIP codes in its places | 35 |
Rate centers in area code 831
| Rate center | Prefixes | Share |
|---|---|---|
| SALINAS | 83 | 21% |
| SANTA CRUZ | 75 | 19% |
| MONTEREY | 64 | 16% |
| WATSONVL | 30 | 7% |
| HOLLISTER | 22 | 5% |
| APTOS | 19 | 5% |
| CARMEL | 12 | 3% |
| BEN LOMOND | 11 | 3% |
| 16 other rate centers | 88 | 22% |
Who holds the prefixes in 831
Pacific Bell holds the most prefixes, 124 (31%). 76% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Pacific Bell | 124 | 31% |
| New Cingular Wireless PCS | 35 | 9% |
| Verizon Wireless | 30 | 7% |
| Onvoy | 29 | 7% |
| Level 3 Communications | 26 | 6% |
| IP Horizon | 14 | 3% |
| 38 other carriers | 146 | 36% |
A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company. Find which carrier a number is on, or browse the prefix holders.
History of area code 831
- 1959-01-01 Area code 408, named as the parent of 831 in the NANPA report, was in service.
- 1998-07-11 Area code 831 went into service.
Area codes nearest to 831
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
ZIP codes in area code 831
35 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Salinas, CA | 8 |
| Santa Cruz, CA | 6 |
| Monterey, CA | 4 |
A ZIP code and an area code are unrelated systems. A ZIP code can sit in more than one area code, and an area code spans many ZIP codes.
Complaints on file for 831 numbers
1,393 FCC complaints are on file for 1,055 numbers in 831, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 60 |
| 2024 | 38 |
| 2025 | 47 |
Other area codes in California
California is one state with 41 area codes in the NANPA table. 831 is one of them.
- 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
Next to 831 in the numbering table
These are the codes just before and after 831 when all are sorted by number. They are neighbours on the list, not necessarily on the map.
What the area code does and does not tell you
A number that starts with 831 was first assigned in California. That is a fact about where the number began, and it is a useful hint when you check a form entry, for example a billing address in California next to a 831 phone number.
It does not show where the person is today. A number stays with its owner after a move or a change of provider (number portability), and mobile numbers travel with the handset. The area code also cannot tell you whether the line is active, who the carrier is, or whether the number is mobile or fixed: the plan shares those ranges. Read more about the area code, the numbering plan and line type.
Check numbers in bulk with the API
| Product | Credits | Docs |
|---|---|---|
| Phone Numbering-Plan Validation | 1 credit per valid number | API docs |
| Phone Intelligence (carrier and line status) | 1 credit per check (invalid numbers outside the US and Canada are free) | Product page |
Questions about area code 831
Where is area code 831?
NANPA assigns area code 831 to California, United States.
In which state does area code 831 sit?
California. 831 is one of 41 area codes the NANPA table assigns to the state.
Which places does area code 831 cover?
The places with the most ZIP codes among the rate centers in 831 are Salinas, CA, Santa Cruz, CA and Monterey, CA. The rate center list on this page shows all of them.
Who owns area code 831?
NANPA assigns area codes. Within 831, Pacific Bell holds the most prefixes, 124 prefixes or 31%.
Which time zone does 831 use?
The NANPA NPA report lists the time zone for 831 as Pacific (P).
What year did 831 enter service?
The NANPA NPA report gives an in-service date of 1998-07-11, so 831 has been in use since 1998.
Does area code 831 have an overlay?
The NANPA NPA report lists no other area code in an overlay with 831.
Which area codes are nearest to 831?
The area codes closest to 831, measured between the centers of the ZIP code places they serve, are 408 (about 27 miles), 669 (about 40 miles), 650 (about 62 miles), 341 (about 83 miles) and 510 (about 83 miles).
How many prefixes does area code 831 have?
NANPA's report dated 2026-10-17 lists 404 prefixes in service in 831, spread over 24 rate centers and 44 holders.
Are there complaints about 831 numbers?
The FCC data on file has 1,393 complaints for 1,055 numbers in 831. They are unverified consumer reports. A number with no complaints on file is not proven safe.
Area code assignments: North American Numbering Plan Administrator NPA report, file dated 10/17/2026, retrieved 2026-10-17. Source file. New codes are assigned several times a year. Prefixes, rate centers, holders, time zone, in-service date and overlays: NANPA central office code report dated 2026-10-17 and NPA report dated 2026-10-18. Complaints: FCC consumer complaints open data, fetched 2026-10-17. ZIP code places: Postal code places and coordinates: GeoNames (geonames.org), licensed CC BY 4.0.