Area code 631: New York
What is area code 631?
Area code 631 is a US state area code for New York, on Eastern Time. It has 782 prefixes in service across 54 rate centers, the largest being Brentwood, Farmingdale and Riverhead. It shares its area with 934, so local numbers there can start with any of them. Local calls there take 10 digits.
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See the phone add-onArea code 631 facts
| Location | New York, United States |
|---|---|
| Time zone | Eastern Time |
| Overlays | 934 |
| Split from | 516 |
| In service since | November 1, 1999 |
| Local calls | 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
In short: 631 is New York (Eastern 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 631
America/New_York
Prefixes in service
782 of 792 possible
54 rate centers
Which cities and towns use area code 631?
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 631 rate centers with the most prefixes in service. 42 smaller ones aren't listed.
| Rate center | Prefixes |
|---|---|
| Brentwood | 127 |
| Farmingdale | 42 |
| Riverhead | 40 |
| Huntington | 34 |
| Central Islip | 32 |
| Amityville | 31 |
| Babylon | 28 |
| Deer Park | 27 |
| Patchogue | 26 |
| Ronkonkoma | 24 |
| Selden | 24 |
| Smithtown | 20 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 631 number?
NANPA's dialling plan for 631: local calls inside the code take 10 digits, toll calls 10 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 631 | 631-555-0147 |
|---|---|
| From another US or Canadian area code | 1-631-555-0147 |
| From outside North America | +1 631 555 0147 |
| E.164, for CRMs and SMS tools | +16315550147 |
When did area code 631 start?
Area code 631 went into service on November 1, 1999, split from 516. Today 631 and 934 cover the same area as an overlay, which is why 10-digit dialling is needed for local calls there.
Tools for 631 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 631 number tells you where it was issued, not what it is now.
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Area code 631 questions
- What state is area code 631?
- Area code 631 is in New York, United States. Its largest rate centers by number of prefixes are Brentwood, Farmingdale, Riverhead, Huntington and Central Islip.
- What time zone is area code 631 in?
- Eastern Time.
- What area codes overlay 631?
- 934. An overlay adds a new code to the same area instead of splitting it, so neighbours can have different area codes and local calls need 10 digits.
- When did area code 631 start?
- Area code 631 went into service on November 1, 1999, split from 516.
- Is a 631 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 631 have?
- 782 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 631 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 631 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 631 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 New York
All New York area codes on the area code index.
212315329332347363465516518585607624646680716718838845914917929934
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.