Chelsea, MA — rate center

NANPA rate center & CO code data, current as of July 28, 2026.

Area codes
617, 857
Active prefixes
16
Carriers
7
Pooled prefixes
12
LATA
128
Metro area
Boston-Cambridge-Newton, MA-NH MSA

Chelsea is a telephone rate center in Massachusetts served by area codes 617, 857. A rate center is the locality the phone industry uses to anchor numbers for billing; every prefix listed below is registered here.

NANPA records show 16 active prefixes here, held by 7 different carriers. Pooling applies to 12 of them — individual thousands-blocks may belong to different companies.

The rate center belongs to the Boston-Cambridge-Newton, MA-NH Metropolitan Statistical Area. Routing-wise it sits in LATA 128.

Because 617, 857 all serve this territory, two Chelsea numbers can look completely different while being neighbors — check the prefix, not just the area code.

As always with US numbering: a prefix anchored to Chelsea tells you where the block was issued. The person calling may have ported the number, moved away, or be spoofing it entirely — verify callers through independently found contact details.

Prefixes anchored to Chelsea

Prefixes anchored to the Chelsea rate center
PrefixCode holderPooled
617-270 METROPCS, INC. Yes
617-336 PAETEC ITEL, LLC Yes
617-370 MCIMETRO ACCESS TRANSMISSION SERVICES LLC Yes
617-409 PAETEC ITEL, LLC Yes
617-461 METROPCS, INC. Yes
617-466 COMCAST IP PHONE, LLC Yes
617-660 VERIZON NEW ENGLAND INC. No
617-819 MCIMETRO ACCESS TRANSMISSION SERVICES LLC Yes
617-884 VERIZON NEW ENGLAND INC. No
617-887 VERIZON NEW ENGLAND INC. No
617-889 VERIZON NEW ENGLAND INC. No
617-958 ONVOY, LLC - MA Yes

FAQ

What area code is Chelsea, MA?

Chelsea is served by 2 area codes — 617, 857 — which overlay the same territory.

How many prefixes does Chelsea have?

16 active NXX prefixes are anchored to this rate center in NANPA records, held by 7 carriers.

Is a call from a Chelsea prefix really from Chelsea?

Not necessarily. The prefix marks where the number block was issued; porting, VoIP and spoofing all detach calls from that geography.