NumberingData
Verified Nov 1, 2026 · Source: NANPA CO Code Assignment Records

FIREISLAND prefixes in area code 631

NANPA records 6 assigned NXX blocks to rate center FIREISLAND in area code 631, 0.8% of the 782 blocks assigned in the code. A rate center is the billing geography a block is allocated to – NANPA truncates the name to ten characters, so read it as a NANPA label rather than a town. 5 holders hold those blocks, the largest being LEVEL 3 COMMUNICATIONS, LLC - NY (2), TC SYSTEMS, INC. - NY (1), VERIZON NEW YORK, INC. (1). The earliest assignment on record here is 2013-10-08 and the most recent 2022-10-11. 6 of them are in thousands-block pooling, so those prefixes are shared between carriers in 1,000-number lots. The same rate center name also appears in area code 934 – overlay codes cover the same geography, so a rate center is served by all of them.

6 assigned blocks – 0.8% of 631
5 holders of record
6 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
631-437 AT&T TC SYSTEMS, INC. - NY 2013-10-08 yes yes
631-440 Lumen LEVEL 3 COMMUNICATIONS, LLC - NY – yes yes
631-570 Lumen LEVEL 3 COMMUNICATIONS, LLC - NY – yes yes
631-583 Verizon VERIZON NEW YORK, INC. – yes yes
631-631 Bandwidth BANDWIDTH.COM CLEC, LLC - NY 2022-10-11 yes yes
631-817 Onvoy ONVOY, LLC- NY – yes yes

The holder is who received the block from the numbering administrator. It is not necessarily the carrier serving a given number: numbers move with their owners, and a pooled block is shared.

Who holds the blocks

HolderBrandBlocksShare here
LEVEL 3 COMMUNICATIONS, LLC - NY Lumen 2 33.3%
TC SYSTEMS, INC. - NY AT&T 1 16.7%
VERIZON NEW YORK, INC. Verizon 1 16.7%
BANDWIDTH.COM CLEC, LLC - NY Bandwidth 1 16.7%
ONVOY, LLC- NY Onvoy 1 16.7%

Frequently asked

Which prefixes belong to FIREISLAND in area code 631?

6 blocks: 437, 440, 570, 583, 631, 817. The table above gives the holder of each.

Which carriers have numbers in FIREISLAND?

LEVEL 3 COMMUNICATIONS, LLC - NY (2 blocks), TC SYSTEMS, INC. - NY (1 block), VERIZON NEW YORK, INC. (1 block), BANDWIDTH.COM CLEC, LLC - NY (1 block), ONVOY, LLC- NY (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is FIREISLAND a city?

It is a rate center – the unit NANPA allocates number blocks to. Its name is abbreviated to ten characters and is not necessarily a settlement: we print it as recorded rather than guess at the full name.

Other rate centers in 631

All 782 prefixes in 631