North American Numbers Source-cited · ownership disclosed
Area code
617
In service
United States · since 1947

Boston

Area code 617 is one of the two original 1947 Massachusetts codes and now covers Boston and its inner-ring communities. It is overlaid by 857 and requires ten-digit dialing.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
Boston
Type
geographic
Status
in service
In service since
1947
Projected exhaust
2066 Q3

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 617 is

Inner-ring Greater Boston within Suffolk, Middlesex, Norfolk, and Essex counties..

Communities served wholly or partly by 617:

BostonCambridgeBrooklineNewtonQuincySomervilleChelseaEverettMiltonWatertown

Original 1947 territory covered the eastern two-thirds of Massachusetts; successive splits reduced it to inner Boston.

B · Relationships

How it relates to other codes

The codes 617 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?

Related · 1947 413 Western Massachusetts (Springfield) The other original 1947 Massachusetts code, covering western Massachusetts.
Spawned · 1988 508 South-central & southeastern Massachusetts (Worcester) 508 split off from 617 on July 16, 1988.
Spawned · 1997 781 Boston suburbs (Route 128 corridor) 781 split off from 617 on September 1, 1997, leaving 617 as inner Boston.
Overlay · 2001 857 Boston (overlay) 857 overlays 617 across the same territory.
What's changing. Overlay complex with 857; ten-digit dialing mandatory since 2001. Per Wikipedia, 617/857 projected to exhaust by 2059.
C · History

How 617 got here

1947
Area code 617 established as one of the original NANP codes, covering eastern Massachusetts.
Source: Wikipedia
1988-07-16
508 split from 617 (western, northern, and southern portions).
Source: Wikipedia
1997-09-01
781 split from 617, leaving 617 coextensive with inner-ring Greater Boston.
Source: Wikipedia
2001-05-02
Area code 857 overlaid onto 617; ten-digit dialing mandatory.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
800
Prefixes available
0
Thousands-blocks assigned
2,175

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

Compare 617 with another code →
Sources
Wikipedia ↗
Area code 617
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.