Area code 831: California
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.
Local time in area code 831
America/Los_Angeles
Prefixes in service
404 of 792 possible
24 rate centers
Area 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 |
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
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- 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.
Other area codes in California
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.