---
title: "Area code 831: California, United States"
url: "https://lookvalid.com/area-code/831.md"
canonical_url: "https://lookvalid.com/area-code/831"
last_updated: "2026-10-23"
type: "reference"
summary: "Area code 831 serves California, United States. Number formats, numbering rules, a live phone validator and the other codes in California."
---

# Area code 831: California, United States

Area code 831 serves California, United States. Number formats, numbering rules, a live phone validator and the other codes in California.

NANPA lists 404 central office codes (prefixes) in use in area code 831, held by 44 holders across 24 rate centers.
Pacific Bell holds the most prefixes, 124 (31%). 76% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
The FCC unwanted-call data has 1,393 complaints on file for 1,055 numbers in 831, most often filed as "Unwanted Calls". These are consumer reports, not findings.

## Facts

- 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

| 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% |

## Carriers

| 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.

## History

- 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.

## Nearest area codes

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).

## ZIP codes

35 ZIP codes fall in places that have a rate center in this area code. The places with the most are Salinas, CA (8 ZIP codes), Santa Cruz, CA (6 ZIP codes) and Monterey, CA (4 ZIP codes). A ZIP code and an area code are unrelated systems, so a ZIP code can sit in more than one area code and an area code spans many ZIP codes.

## Complaints on file

1,393 complaints for 1,055 numbers. Numbers whose latest complaint falls in each year:

- 2023: 60
- 2024: 38
- 2025: 47

## Questions

### 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.

Sources: NANPA central office code report dated 2026-10-17; NANPA NPA report dated 2026-10-18; FCC unwanted-call complaints, data fetched 2026-10-17; ZIP code places from GeoNames (CC BY 4.0).