516 Area Code: Nassau County's Long Island Number

The 516 area code is Nassau County, New York — the western half of Long Island, pressed between the Queens border and Suffolk County. It has carried Long Island numbers since 1951, and since January 20, 2023 it shares the county with the 363 overlay.

Code and county are nearly interchangeable here, and that tidy match took decades to arrive. Nassau is the American postwar suburb in concentrated form — its area code grew up alongside it, shedding territory decade by decade until 516 meant Nassau and nothing else.

Where 516 works

516 covers all of Nassau County: Hempstead, Levittown, Freeport, Glen Cove, Garden City, Mineola, Hicksville, Long Beach, Massapequa, Great Neck, and the rest of a county of roughly 1.4 million people. NANPA’s relief map draws the borders plainly — Queens and its 347/718/917/929 codes to the west, Suffolk’s 631 and its 934 overlay to the east, and 914 across the Long Island Sound.

That western border does real work. A 516 number says “Long Island, not the city” — the county line between Nassau and Queens is also the line where New York City’s numbering complex ends and the suburbs’ own code begins.

Born in the suburban boom

When AT&T drew the original numbering plan in 1947, Long Island didn’t get its own code — Nassau and Suffolk dialed under 914 along with the lower Hudson Valley. The same year, Levitt & Sons broke ground in a Nassau potato field on what became Levittown, the prototype postwar suburb.

The growth that followed overwhelmed the numbering plan almost immediately. In 1951, Nassau and Suffolk were split off from 914 as their own numbering plan area: 516, covering all of Long Island. For the next half century, that was the arrangement — one code from the Queens line to Montauk.

It was a productive half century for the code. Grumman’s plants in Bethpage — deep in 516 territory — built every Apollo lunar module; six descent stages still sitting on the Moon carry “Made in Bethpage, New York” nameplates. Between the aerospace payrolls and the subdivisions, 516 became one of the busiest suburban codes in the country.

November 1, 1999: Suffolk leaves

By the late 1990s one code could no longer feed both counties, and regulators chose a split over an overlay. On November 1, 1999, Suffolk County moved to the new 631 area code, with permissive dialing of the old digits running into spring 2000. Nassau kept 516.

That split created today’s tidy map: 516 for Nassau, 631 (now overlaid by 934) for Suffolk. It also made 516 a shorthand. On a county line where towns blur together, the first three digits still tell Long Islanders which side of the border a number was born on — the mechanics behind that are in our guide to how area codes work.

The 988 twist: ten digits before the overlay

Nassau’s seven-digit dialing didn’t end because of the overlay — it ended because of a suicide-prevention hotline. When the FCC designated 988 as the national crisis line, every area code that still allowed seven-digit dialing and had 988 in use as a local prefix had to change. NANPA’s Planning Letter PL-556 lists 82 such codes, and 516 is one of them, alongside New York’s 607, 716, 845, and 914.

The schedule: permissive ten-digit dialing from April 24, 2021, mandatory from October 24, 2021. So by the time overlay preparations began, Nassau callers were already dialing ten digits — the one disruptive step of an overlay had happened in advance, for an entirely different reason.

363: the overlay over Nassau

The numbers still ran short. On January 20, 2022, the New York Public Service Commission approved an all-services overlay for the 516 region in Case 21-C-0473, and NANPA’s Planning Letter PL-581 set the new code’s in-service date: 363 went live on January 20, 2023, covering the identical Nassau County footprint.

PL-581 contains a detail worth knowing: 363 prefixes become available for assignment only once the assignable 516 prefixes are exhausted. In practice that made 363 numbers scarce at first — carriers kept issuing 516 stock while it lasted. A 363 number is simply the newest kind of Nassau number: same coverage, same cost, same localness, issued from the younger pool.

What a 516 call actually tells you

Less than instinct suggests. What the code records is where a number was issued; where the caller sits is another matter — numbers port, VoIP dials from anywhere, and caller ID can be spoofed outright, including neighbor-spoofed digits that mirror your own 516 prefix.

The reliable habit: treat the display as unverified. A genuine Nassau school district, medical office, or town department survives an independent callback to a number you look up; a spoofed one does not.

A 516 number for your business

For the trades, medical practices, law offices, and home-services businesses that live on local calls, a 516 display is the difference between “my plumber” and “some sales call” — our local presence dialing guide lays out the answer-rate math. Operations based elsewhere that serve Long Island customers can hold Nassau numbers too; provisioning is by rate center, in 516 or 363 alike.

SIPNEX provisions Nassau County DIDs and delivers them over SIP trunking to any phone system, with every outbound call signed at A-level STIR/SHAKEN attestation under our own certificate — the trust signal a spoofed 516 can’t carry.

Frequently asked questions

SIPNEX is an FCC-licensed carrier providing local DID numbers across Long Island and every US market, toll-free numbers as a registered RespOrg, and dialer-grade SIP trunking — every call signed with our own STIR/SHAKEN certificate at A-level attestation. Call (833) 665-2220, talk to an operator, or see rates.