The 631 area code covers Brentwood, Farmingdale and 49 more places in New York.
Area code 631 is in New York, on Eastern Time. In the 631 area, phone numbers are given out most in Suffolk County, then Nassau County. It has been in service since November 1, 1999. 934 covers the same area, so two neighbours can have different area codes.
- Where
- Suffolk County and Nassau County, New York
- Time zone
- Eastern Time
- In service since
- November 1, 1999
- Shares its area with
- 934 (since 2016)
- Prefixes in use
- 782
- How to dial
- Local calls need all 10 digits: 631-555-0142.
Find out who called you from a 631 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (631) number is on today, use our free carrier lookup.
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Brentwood holds 16% of the phone prefixes in area code 631.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 782 prefixes in use shows where 631 numbers are actually given out.
- Brentwood127 prefixes, 16%
- Farmingdale42 prefixes, 5%
- Riverhead40 prefixes, 5%
- Huntington34 prefixes, 4%
- Central Islip32 prefixes, 4%
- Amityville31 prefixes, 4%
- Babylon28 prefixes, 4%
- Deer Park27 prefixes, 3%
Also served: Patchogue, Ronkonkoma, Selden and Smithtown and 39 smaller places.
Of the carriers named here, Cablevision Lightpath, Level 3 (Lumen) and T-Mobile hold the most phone number prefixes in area code 631, 55 prefixes each.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 782 prefixes in use in 631 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| Cablevision Lightpath | 55 | 7% |
| Level 3 (Lumen)Lumen's business and wholesale network | 55 | 7% |
| T-MobileMobile network | 55 | 7% |
| AT&T MobilityMobile network | 49 | 6% |
| TC Systems | 34 | 4% |
| PAETEC (Windstream)Windstream's business phone network | 32 | 4% |
| 30 other carriers | 502 | 64% |
77% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
631 has been overlaid once since 1999.
1999
631 starts on November 1, 1999, split off from 516.
2016
On July 16, 2016, 934 is added on top of 631, so new numbers here can get either code.
A 631 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 631 are 203, 516 and 860.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
New York has 22 other area codes.
These are the questions people ask most about area code 631.
Where is area code 631?
631 covers Brentwood, Farmingdale, Riverhead and Huntington and 47 more places in New York. In the 631 area, phone numbers are given out most in Suffolk County, then Nassau County.
What state is area code 631 in?
New York. 631 is a New York area code on Eastern Time.
What cities use area code 631?
The places holding the most 631 prefixes are Brentwood, Farmingdale, Riverhead, Huntington, Central Islip, Amityville, Babylon and Deer Park, out of 51 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 631?
No single phone company owns 631. NANPA's records list its 782 prefixes across many carriers, and the ones named on this page include Cablevision Lightpath, Level 3 (Lumen) and T-Mobile. Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 631 in?
631 is on Eastern Time.
When did area code 631 start?
631 went into service on November 1, 1999, when it was split off from 516.
Is 631 the same area as 934?
Yes. 934 (since 2016) covers the same ground as 631. Nobody's number changed when it was added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.
How do I dial a 631 number?
Local calls need all 10 digits: 631-555-0142.
Is 631 a toll-free number?
No. 631 is a regular area code for Brentwood and Farmingdale in New York, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 631?
The closest are 203/475 (New Haven, Connecticut), 516/363 (Nassau County, New York), 860/959 (Hartford, Connecticut) and 914 (Westchester County, New York), measured between the centres of each area.
Who called me from a 631 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 631 a scam?
631 is a real New York area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.