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

SOMERVILLE prefixes in area code 857

NANPA records 8 assigned NXX blocks to rate center SOMERVILLE in area code 857, 2.2% of the 361 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. 7 holders hold those blocks, the largest being ONVOY, LLC - MA (2), MCIMETRO ACCESS TRANSMISSION SERVICES LLC (1), COMMIO, LLC (1). The earliest assignment on record here is 2001-05-03 and the most recent 2024-11-07. 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 codes 617, 901, 908, 979 – overlay codes cover the same geography, so a rate center is served by all of them.

8 assigned blocks – 2.2% of 857
7 holders of record
8 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
857-227 Verizon MCIMETRO ACCESS TRANSMISSION SERVICES LLC 2001-05-23 yes yes
857-388 COMMIO, LLC 2021-09-24 yes yes
857-467 TON80 COMMUNICATIONS, LLC 2022-02-24 yes yes
857-523 Verizon CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MA 2001-05-03 yes yes
857-575 Onvoy ONVOY, LLC - MA 2021-04-01 yes yes
857-822 Charter ONVOY SPECTRUM, LLC 2024-11-07 yes yes
857-995 Onvoy ONVOY, LLC - MA – yes yes
857-997 HD CARRIER LLC – 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
ONVOY, LLC - MA Onvoy 2 25%
MCIMETRO ACCESS TRANSMISSION SERVICES LLC Verizon 1 12.5%
COMMIO, LLC – 1 12.5%
TON80 COMMUNICATIONS, LLC – 1 12.5%
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MA Verizon 1 12.5%
ONVOY SPECTRUM, LLC Charter 1 12.5%
HD CARRIER 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 SOMERVILLE in area code 857?

8 blocks: 227, 388, 467, 523, 575, 822, 995, 997. The table above gives the holder of each.

Which carriers have numbers in SOMERVILLE?

ONVOY, LLC - MA (2 blocks), MCIMETRO ACCESS TRANSMISSION SERVICES LLC (1 block), COMMIO, LLC (1 block), TON80 COMMUNICATIONS, LLC (1 block), CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MA (1 block), ONVOY SPECTRUM, 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 SOMERVILLE 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 857

All 361 prefixes in 857