Nassau County (overlay)

All-service overlay of area code 516, covering Nassau County on Long Island.

The essentials Numbering data · NumberResearch · as of 2026-09-18

Place

Type

geographic

Status

in service

In service since

2023

Projected exhaust

2073 Q2

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 363 is

Nassau County, Long Island, New York.

Communities served wholly or partly by 363:

HempsteadLong BeachGlen CoveFreeportLevittown

Representative Nassau County communities; shares 516's footprint.

B · Relationships

How it relates to other codes

The codes 363 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Overlay · 2023 516 Nassau County Overlays all of 516 (Nassau County).

Related · 1999 631 Suffolk County Adjacent Suffolk County code, itself split from 516.

What's changing. Active overlay of 516 for Nassau County; ten-digit dialing in effect.

C · History

How 363 got here

2023-01-20

Announced to overlay 516 to address projected Q2 2023 exhaustion.

Source: Wikipedia 516/363

D · Capacity

How full it is

Prefixes assigned

Prefixes available

748

Thousands-blocks assigned

323

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 363 with another code →

Sources

Wikipedia (secondary) ↗

Area codes 516 and 363

NumberResearch.org ↗

Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.