Area code 831: California
What is area code 831?
Area code 831 is a US state area code for California, on Pacific Time. It has 404 prefixes in service across 24 rate centers, the largest being Salinas, Santa Cruz and Monterey. NANPA lists no overlay code for it. Local calls there take 7 digits. The code never shows a line is in service.
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See the phone add-onArea code 831 facts
| Location | California, United States |
|---|---|
| Time zone | Pacific Time |
| Overlays | None |
| Split from | 408 |
| In service since | July 11, 1998 |
| Local calls | 7 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
In short: 831 is California (Pacific Time). Format checks here are free and run in your browser; the current carrier and line type need a live lookup. Bulk phone number validator · Pro + Phone plan
Local time in area code 831
America/Los_Angeles
Prefixes in service
404 of 792 possible
24 rate centers
Which cities and towns use area code 831?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 831 rate centers with the most prefixes in service. 12 smaller ones aren't listed.
| Rate center | Prefixes |
|---|---|
| Salinas | 83 |
| Santa Cruz | 75 |
| Monterey | 64 |
| Watsonville | 30 |
| Hollister | 22 |
| Aptos | 19 |
| Carmel | 12 |
| Ben Lomond | 11 |
| Felton | 9 |
| Boulder Creek | 9 |
| Soledad | 8 |
| Greenfield (Monterey) | 7 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 831 number?
NANPA's dialling plan for 831: local calls inside the code take 7 digits, toll calls 7 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 831 | 555-0147 |
|---|---|
| From another US or Canadian area code | 1-831-555-0147 |
| From outside North America | +1 831 555 0147 |
| E.164, for CRMs and SMS tools | +18315550147 |
When did area code 831 start?
Area code 831 went into service on July 11, 1998, split from 408. It has no overlay, so every number in its area still starts with it.
Tools for 831 numbers
- Bulk phone number validator
Format, country and number type for every number in a CSV, with E.164 output.
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- Area code time zone
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- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 831 number tells you where it was issued, not what it is now.
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Area code 831 questions
- What state is area code 831?
- Area code 831 is in California, United States. Its largest rate centers by number of prefixes are Salinas, Santa Cruz, Monterey, Watsonville and Hollister.
- What time zone is area code 831 in?
- Pacific Time.
- Does area code 831 have an overlay?
- Not as of NANPA's file dated 10/16/2026. Every number in its area uses 831.
- When did area code 831 start?
- Area code 831 went into service on July 11, 1998, split from 408.
- Is an 831 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 831 have?
- 404 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
- Does a valid format mean a 831 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 831 is an assigned code. It cannot tell whether the number is connected, who answers it or which carrier serves it today, because numbers are reassigned and ported. A live carrier lookup reports the current carrier and line type, but even that is not proof someone answers.
- Can I check a list of 831 numbers for free?
- Yes. Paste them in the list tab above or upload a CSV to the bulk phone number validator: format, E.164, country and the numbering-plan line type are free for every row, with no account. Live carrier and line-type lookups come with Pro + Phone at $49.99/mo (5,000 a month).
Other area codes in California
All California area codes on the area code index.
209213279310323341350357369408415424442510530559562619626628650657661669707714738747760805818820837840858909916925949951
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.