North American Numbers Source-cited · ownership disclosed
Area code
351
In service
United States · since 2001

North central & northeastern Massachusetts (overlay)

Area code 351 is an overlay of 978, serving north central and northeastern Massachusetts. It shares its full geography with 978 and requires ten-digit dialing.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
North central & northeastern Massachusetts (overlay)
Type
geographic
Status
in service
In service since
2001
Projected exhaust
2157 Q4

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 351 is

North central and northeastern Massachusetts (LATA 128); bordered by New Hampshire to the north, 413 to the west, 339/781 to the south, and the Atlantic Ocean to the northeast..

Communities served wholly or partly by 351:

LowellLawrenceHaverhillFitchburgLeominsterSalemPeabodyGloucester

Same service area as 978; the two codes are geographically identical.

B · Relationships

How it relates to other codes

The codes 351 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Overlay · 2001 978 North central & northeastern Massachusetts (Lowell) 351 overlays 978 across the same territory.
Related · 1997 508 South-central & southeastern Massachusetts (Worcester) 978 (and thus 351) split from 508 in 1997.
What's changing. Overlay of 978; ten-digit dialing mandatory. Both codes well supplied (per Wikipedia, exhaustion not projected until the 2150s).
C · History

How 351 got here

2001-05-02
Area code 351 activated as an overlay of 978; ten-digit dialing mandatory.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
110
Prefixes available
690
Thousands-blocks assigned
710

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 351 with another code →
Sources
Wikipedia ↗
Area code 351
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.