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

OLDGRNWICH prefixes in area code 203

NANPA records 9 assigned NXX blocks to rate center OLDGRNWICH in area code 203, 1.1% of the 784 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 MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT (5), SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT (2), CABLEVISION LIGHTPATH, INC. - CT (1). The earliest assignment on record here is 2003-04-16 and the most recent 2005-01-31. 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 475 – overlay codes cover the same geography, so a rate center is served by all of them.

9 assigned blocks – 1.1% of 203
4 holders of record
8 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
203-277 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT 2003-04-16 yes yes
203-344 Altice CABLEVISION LIGHTPATH, INC. - CT – yes yes
203-369 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT 2003-10-07 yes yes
203-409 AT&T TELEPORT COMMUNICATIONS AMERICA, LLC - CT – yes yes
203-637 AT&T SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT – no yes
203-698 AT&T SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT – yes yes
203-827 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT 2004-07-19 yes yes
203-986 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT 2004-02-20 yes yes
203-990 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT 2005-01-31 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
MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT Verizon 5 55.6%
SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT AT&T 2 22.2%
CABLEVISION LIGHTPATH, INC. - CT Altice 1 11.1%
TELEPORT COMMUNICATIONS AMERICA, LLC - CT AT&T 1 11.1%

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 OLDGRNWICH in area code 203?

9 blocks: 277, 344, 369, 409, 637, 698, 827, 986, 990. The table above gives the holder of each.

Which carriers have numbers in OLDGRNWICH?

MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CT (5 blocks), SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT (2 blocks), CABLEVISION LIGHTPATH, INC. - CT (1 block), TELEPORT COMMUNICATIONS AMERICA, LLC - CT (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is OLDGRNWICH 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 203

All 784 prefixes in 203