Introduction
The 631 area code covers Suffolk County on Long Island, New York, from Huntington and Babylon in the west to Montauk at the island's eastern end. It was carved out of 516 on November 1, 1999, and since July 16, 2016, it has shared Suffolk with the overlay code 934.
An unknown 631 call usually means someone with a Suffolk County line is trying to reach you, though caller ID can't confirm that. This guide walks through the towns in the code, its time zone, the 934 overlay and the dialing change that came with it, the country code question, and how a business can get a 631 number.
- 631 serves all of Suffolk County, including Huntington, Islip, Brookhaven, Riverhead, Southampton and East Hampton.
- It split from 516 on November 1, 1999, when Nassau County kept 516.
- 934 overlays 631. Ten-digit local dialing became mandatory on June 18, 2016, and 934 numbers followed on July 16, 2016.
- Suffolk keeps Eastern Time. From abroad the number starts +1 631, because 631 is an area code, not a country code.
Where Is the 631 Area Code?
Area code 631 is in New York State, on Long Island. An overlay notice filed with the New York Department of Public Service puts it plainly: 631 serves all of the communities in Suffolk County, and the overlay code 934 serves exactly the same area.
Suffolk's western boundary is the Nassau County line, where numbers change to 516 and 363. Everything east of that line, out to Greenport and Montauk, falls within 631. If you're comparing Long Island codes, remember that 516 now means Nassau alone.
Our New York area codes page lists the codes for the rest of the state, including New York City and upstate regions.
Towns and Communities in the 631 Area Code
New York State describes Suffolk County as the central and eastern part of Long Island, divided into ten towns, and every one of the ten is in the 631 area:
- Babylon, Huntington, Islip and Smithtown
- Brookhaven
- Riverhead, the county seat
- Southampton, East Hampton, Southold and Shelter Island
Places marked on the overlay map filed with regulators, including Northport, Patchogue, Riverhead, Greenport and Montauk, all sit inside the single 631/934 zone. The code alone won't tell you whether a caller is in a South Shore village or on the East End.
One wrinkle dates from the 1999 split. The Public Service Commission let existing wireless customers in Suffolk keep their 516 numbers if they chose, and it later let wireless carriers decide whether their existing Suffolk number blocks stayed in 516 or moved to 631. That is why some Suffolk cell phone users held on to 516 numbers after the county got its own code.
631 Area Code Time Zone (Eastern Time)
All of Suffolk County uses Eastern Time, from the Nassau line to Montauk Point, and NANPA lists Eastern as the time zone for both 631 and 934.
That means UTC-5 during Eastern Standard Time and UTC-4 during Eastern Daylight Time, which lasts from the second Sunday in March to the first Sunday in November. A caller in Seattle who wants to reach an Islip office when it opens at 9 a.m. needs to dial at 6 a.m. Pacific Time.
631 and 934: One Area, Two Area Codes
Suffolk shared a code with Nassau for decades, first 914 and then, from 1951, 516. The commission's Opinion No. 99-6, issued April 29, 1999, split the county off; NANPA picked 631 for Suffolk on May 19, and the new code went into service on November 1, 1999. Callers could still reach Suffolk numbers through 516 during a permissive period that ended April 1, 2000.
Sixteen years later the county was running short again, and this time the commission chose an overlay (Case 14-C-0182). Adding 934 on top of 631 meant no existing number changed. The trade-off was the end of seven-digit local calls, phased in over a year:
| Date | What changed |
|---|---|
| July 18, 2015 | Ten-digit local dialing encouraged; seven-digit calls still connect |
| June 18, 2016 | Ten-digit dialing required; seven-digit calls reach a recording |
| July 16, 2016 | New lines and services may be assigned 934 numbers |
The overlay notice filed with the Department of Public Service also promised that phone numbers, local calling areas and call prices would stay the same, and they did: the overlay changed how people dial, not what they pay.
Is 631 a Country Code? What That Search Really Means
The search "631 country code" is common, especially from outside the US, but 631 isn't a country code. It is a North American area code, and the country code in front of it is 1, which covers the United States along with Canada and other countries in the North American Numbering Plan.
Written for international callers, a Suffolk County number looks like +1 631 555 0164. The plus sign stands for the international access code of the caller's own network; after it come the country code 1, then 631 and the local seven digits. Searches for "1 631" are the same number with the country code attached; our US country code guide has more on +1.
631 Area Code vs ZIP Codes
A "zip code 631" doesn't exist. The Postal Service divides Suffolk County into many ZIP Codes for mail delivery, while the phone network treats the entire county as one area served by 631 and 934. Neither system was drawn with the other in mind.
So a Riverhead business and a Babylon household can share an area code but not a ZIP Code. When you need a postal code, search the address with the Postal Service. When you need the area code, the answer anywhere in Suffolk is 631 or 934.
How to Tell If a Call From 631 Is Legitimate
A 631 number on your screen tells you where the line was assigned and nothing about the caller's intentions. Real Suffolk businesses, schools and medical offices call from 631 all the time, and a scammer can make a call appear to come from a Long Island number just as easily.
- The caller claims to be from a government agency, bank or utility and says you must act today.
- You're told to pay with a gift card, cryptocurrency, a wire transfer or a payment app.
- The caller asks for a password, your Social Security number or a one-time code sent to your phone.
- A recorded message offers a prize, a refund or a lower rate if you press a key.
If any of those come up, end the call and contact the organization directly using a number from its official website or your bill. Report the attempt at ReportFraud.ftc.gov, list your number on the National Do Not Call Registry to cut telemarketing, and block the caller from your phone's call log.
How to Dial a 631 Phone Number
Since June 18, 2016, every local call in Suffolk County has needed the area code. Dial only seven digits and the call won't go through; a recording tells you to hang up and try again.
- Suffolk to Suffolk: ten digits, 631 or 934 plus the number, such as 631-555-0164.
- Suffolk to another area code, including Nassau's 516: 1 plus the area code and number, for example 1-516-555-0119.
- Into Suffolk from abroad: your exit code, then 1, 631 and the number.
- Emergencies and service lines: 911, and 211 through 811 where available, still take three digits.
The 2016 switch also meant reprogramming devices that dialed seven digits on their own, such as alarm systems, medical alert devices, PBX phone systems and speed dialers. If an older device in a Suffolk home or office still fails to connect, check that first.
How to Get a 631 Phone Number for Your Business
A business based in Suffolk, or one that wants to serve customers there, can present a local 631 number instead of a number from another region. If customers already know your number, keeping it matters as much as the code, and porting lets you keep it when you change providers.
Start by choosing a local number from the area codes Ringflow offers; Ringflow's search shows whether 631 numbers are available. Then:
- 1Pick the 631 number that is easiest to say out loud and write on a sign.
- 2Route calls to Ringflow's mobile and desktop apps, so a crew in the field and staff in the office can answer.
- 3Set up an auto attendant with separate options for hours, directions or departments.
- 4Turn on business texting, or port an existing 631 number instead of starting over.
Conclusion
The 631 area code has meant Suffolk County since November 1, 1999, when Long Island's shared code was split at the Nassau line. The 934 overlay now serves the county alongside it, local calls take ten digits, and the whole area keeps Eastern Time.
Ringflow is one way to put a Suffolk number to work. Check its area codes for 631 availability, answer on the mobile or desktop app, let an auto attendant handle after-hours callers, and try it on a free trial before porting any number you want to keep.
Ready when you are
Want a Suffolk County Number for Your Business?
Choose a local number from the area codes Ringflow offers and take calls on mobile and desktop apps, with an auto attendant and texting. Start a free trial or port your current number.
FAQ
The 631 area code is in Suffolk County, New York, on the eastern part of Long Island. It covers all ten Suffolk towns, from Babylon and Huntington to Southold and East Hampton. Nassau County, to the west, uses 516 and 363.
Suffolk County is on Eastern Time, the zone used across New York State. Expect EST, five hours behind UTC, in the colder months and EDT, four hours behind UTC, from March to November.
Yes. Area code 934 overlays 631 across all of Suffolk County. New lines could be assigned 934 numbers starting July 16, 2016, and ten-digit dialing for local calls has been required since June 18, 2016.
No. 631 is an area code in the United States, which uses country code +1. Callers in other countries reach Suffolk County by dialing +1 631 and the seven-digit number.
A 631 number alone doesn't mean spam. Many Suffolk County homes and businesses use the code, and caller ID can be faked. Hang up on callers who demand urgent payment, gift cards or verification codes, and report scams at ReportFraud.ftc.gov.
Sign up with a cloud phone provider that offers New York local numbers. Ringflow lets you check whether 631 numbers are available among its area codes, route calls to mobile and desktop apps and add an auto attendant. Porting brings an existing 631 line along.
