Area codes 516 and 363 aretelephoneoverlayarea codes in theNorth American Numbering Plan (NANP) for theU.S. state ofNew York. The numbering plan area (NPA) comprisesNassau County onLong Island. Area code 516 was created in 1951 and 363 was added to the numbering plan area in 2023.
When theAmerican Telephone and Telegraph Company (AT&T) established the first nationwidetelephone numbering plan forOperator Toll Dialing in October 1947, Nassau andSuffolk counties, the lowerHudson Valley, and some areas adjacent were assignedarea code 914. At the time, this area was largely coextensive with the New York state portion of theNew York metropolitan area. In 1951, Nassau and Suffolk were designated as a separate numbering plan area (NPA) with area code 516.[1]
Despite Long Island's growth in both population and telephone service during the second half of the 20th century, this configuration remained for five decades. By the late 1990s, the proliferation of pagers and cell phones required further division to provide more telephone numbers for Long Island. On November 1, 1999, Suffolk was separated as a new numbering plan area witharea code 631, while Nassau retained 516.Permissive dialing of 516 across Long Island continued until spring 2000.[2]
Prior to October 2021, area code 516 had telephone numbers assigned for thecentral office code 988. In 2020,988 was designated nationwide as a dialing code for theNational Suicide Prevention Lifeline, which created a conflict for exchanges that permitseven-digit dialing. This area code was therefore scheduled to transition toten-digit dialing by October 24, 2021.[3]
A 2021 NANP analysis of numbering resources projects exhaustion of NPA 516 during the second quarter of 2023.[4] As a result, additional relief was expected. An overlay of 516 with a new area code was recommended, although a boundary-extension overlay was also considered which would have expanded area code 934 (overlaying 631) to also overlay 516.[5] In January 2022, the new area code 363 was announced to overlay 516 on January 20, 2023.[6][7]
| North:914,203/475 | ||
| West:347/718/929,917 | 516/363 | East:631/934 |
| South:Atlantic Ocean |
40°44′N73°38′W / 40.74°N 73.63°W /40.74; -73.63
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