Nassau County residents can expect a new area code. The new digits 363 will go into service Jan. 20. NewsdayTV's Steve Langford reports.  Credit: Newsday / James Carbone

For more than 70 years, 516 has been the only area code assigned to Nassau County. Soon, callers will have a new trio of numbers to learn: 363.

Phone service carriers can begin assigning 363 to the start of new phone numbers issued in Nassau County at some point after the area code goes into service Jan. 20, the North American Numbering Plan Administrator told Newsday.

It marks the start of an adjustment period for those looking to call or text someone in the county of nearly 1.4 million residents.

“I hope I can remember it,” said Lisa Klein of North Babylon with a laugh.

A fourth Long Island area code became necessary once it was determined that all 10-digit phone numbers in 516 would soon run out.

There are currently just 20 prefixes — the first three digits of a seven-digit number — remaining for the 516 area code, down from the initial 792.

Until the remaining combinations are fully exhausted, carriers cannot assign the 363 area code.

While the most recent estimate from NANPA states that the existing area code will likely reach its prefix limit in the first quarter of 2024, the end date has fluctuated over the past year with earlier projections putting it as soon as spring 2023.

“The timing is difficult to estimate,” said Heidi Wayman, data management manager for NANPA, which oversees the assigning of area codes nationwide.

Ultimately, the new area code will not affect customers with an existing 516 phone number. Those numbers will remain the same under an "overlay" — multiple area codes for the same geographic area. But a request for new service, an additional line, or a move in the location of service will eventually be met with a seven-digit phone number and 363 as the area code, according to the state Public Service Commission, which formally announced the addition of 363 last January.

Calls placed between 516 and 363 will be considered local and rates will not change.

“Overlays are the least disruptive form of area code relief for consumers and can be effectively and efficiently implemented with minimal technical issues,” Alexander Moore, counsel for Verizon, wrote to the Public Service commission in a 2021 joint letter from Verizon, AT&T and T-Mobile endorsing 363.

The 363 area code is projected to provide telephone number relief to Nassau County for the next 49 years. A second alternative considered by NANPA was the elimination of the geographic boundary between the 516 area code in Nassau and 631/934 area codes in Suffolk. But it was later determined that the option would have meant the number of available prefixes maxing out in 22 years, according to a 2021 Public Service Commission report.

Government agencies and phone companies have said they are taking all the necessary action to prepare customers for the change.

Carriers were required to remind customers of the pending area code change in November and December and to caution that 363 callers will need to dial all 10 digits.

Wayman said educating customers to use 10 digits is “one of the biggest hurdles” when introducing a new area code.

Carriers currently issuing 516 area codes were required to make 10-digit dialing mandatory in July to help the transition in Nassau County.

The Public Service Commission said customers should ensure that all services and equipment they use, including life safety and security systems, recognize the new 363 area code as valid. 

The 516 area code has been used on Long Island since 1951. Until July 1999, 516 serviced the entire Island. That year, the Island was split into two, with Nassau keeping 516 and Suffolk getting 631. Suffolk got 934 in 2016.

The move from 516 to 631 in 1999 was met with concern, particularly from residents and business owners on the Nassau-Suffolk border, who at the time told Newsday they worried about the difficulty keeping track of the geographic change.

But more than two decades later, technology and the mobility of phone customers, has lessened concern over the coming change.

Beth Granger of Port Washington noted that because of the rise in cellphone use many people now keep their number as they move around.

“It sort of doesn’t matter anymore,” she said.

Wayman agreed that phone numbers are no longer the geographic indicators they once were.

“You are seeing a shift in thinking,” she said.

The 363 area code will be the first to officially launch in the United States in 2023, NANPA said. The most recent addition was in North Carolina in October.

Following Nassau County, new area codes are expected to launch in Missouri and Illinois in February.

With Steve Langford

What to know

  • The new 363 area code will be put into service in Nassau County on Jan. 20, 2023.
  • Residents with an existing 516 phone number will see no change to their numbers, service or the rates they pay.
  • New 363 phone numbers will not be assigned by carriers until all 516 numbers have been fully exhausted. While that could be any time after Jan. 20, current projections suggest it might not happen for another year.

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