South Boston, MA — rate center

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

In NANP numbering, South Boston, Massachusetts is a rate center — the anchor point for local numbers. It is reached through 617, 857 (multiple area codes serve it).

NANPA records show 19 active prefixes here, held by 10 different carriers. Pooling applies to 17 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 South Boston 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 South Boston 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 South Boston

FAQ

What area code is South Boston, MA?

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

How many prefixes does South Boston have?

19 active NXX prefixes are anchored to this rate center in NANPA records, held by 10 carriers.

Is a call from a South Boston prefix really from South Boston?

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