Area Code 631

About Area Code 631

Area code 631 is a geographic telephone area code assigned to Brentwood, New York. It operates in the Eastern time zone and was first introduced in 1999. Split from 516. Suffolk County Long Island. Overlay 934 (2016).

Within New York, area code 631 shares numbering capacity with 18 other area codes. The state's 19,571,216-person population (2023 Census Bureau estimate) is served by a combined 19 active codes, with 631 primarily responsible for the Brentwood region. New York's state capital is Albany, and its largest city is New York City.

When you receive a call from a 631 number on your Caller ID, the call originated from a phone number assigned to the 631 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 631 only confirms where the number was originally assigned.

Where is the 631 area code located?

Area code 631 is assigned to Brentwood, New York, in the Eastern time zone. The state of New York uses 19 active area codes, and 631 is one of them. Calls placed from the 631 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 631 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Eastern time zone observes Daylight Saving Time, shifting from UTC-5 to UTC-4 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 631 area code?

The 631 area code serves 8 notable cities, listed below in order of population. The largest city in the 631 territory is New York City (8,335,897 residents in Unknown County).

• New York City, NY — 8,335,897 residents (88.5% of 631 numbers)
• Buffalo, NY — 278,349 residents (3% of 631 numbers)
• Rochester, NY — 211,328 residents (2.2% of 631 numbers)
• Yonkers, NY — 201,344 residents (2.1% of 631 numbers)
• Syracuse, NY — 142,749 residents (1.5% of 631 numbers)
• Albany, NY — 101,228 residents (1.1% of 631 numbers)
• New Rochelle, NY — 81,386 residents (0.9% of 631 numbers)
• Mount Vernon, NY — 71,901 residents (0.8% of 631 numbers)

Phone number format in area code 631

All phone numbers within area code 631 follow the standard North American 10-digit format:(631) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 631 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 631 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 631

Split from 516. Suffolk County Long Island. Overlay 934 (2016).

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 631 area code safe to answer?

Area code 631 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 631 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.