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

CLOSTER prefixes in area code 551

NANPA records 8 assigned NXX blocks to rate center CLOSTER in area code 551, 2.7% of the 300 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. 4 holders hold those blocks, the largest being OMNIPOINT COMMUNICATIONS, INC. - NJ (3), ONVOY, LLC - NJ (3), AIRUS, INC. - NJ (1). The earliest assignment on record here is 2014-11-14 and the most recent 2024-10-01. 8 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 201 – overlay codes cover the same geography, so a rate center is served by all of them.

8 assigned blocks – 2.7% of 551
4 holders of record
8 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
551-236 T-Mobile OMNIPOINT COMMUNICATIONS, INC. - NJ 2014-11-14 yes yes
551-248 AIRUS, INC. - NJ 2015-08-12 yes yes
551-288 Onvoy ONVOY, LLC - NJ 2020-09-23 yes yes
551-303 T-Mobile OMNIPOINT COMMUNICATIONS, INC. - NJ 2019-01-28 yes yes
551-346 T-Mobile OMNIPOINT COMMUNICATIONS, INC. - NJ 2022-01-27 yes yes
551-395 Onvoy ONVOY, LLC - NJ 2024-05-29 yes yes
551-406 Onvoy ONVOY, LLC - NJ 2024-10-01 yes yes
551-755 FRACTEL, LLC 2021-08-11 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
OMNIPOINT COMMUNICATIONS, INC. - NJ T-Mobile 3 37.5%
ONVOY, LLC - NJ Onvoy 3 37.5%
AIRUS, INC. - NJ – 1 12.5%
FRACTEL, LLC – 1 12.5%

Same rate center in other codes

Overlay codes cover the same geography, so one rate center is served by all of them.

Frequently asked

Which prefixes belong to CLOSTER in area code 551?

8 blocks: 236, 248, 288, 303, 346, 395, 406, 755. The table above gives the holder of each.

Which carriers have numbers in CLOSTER?

OMNIPOINT COMMUNICATIONS, INC. - NJ (3 blocks), ONVOY, LLC - NJ (3 blocks), AIRUS, INC. - NJ (1 block), FRACTEL, LLC (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is CLOSTER 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 551

All 300 prefixes in 551