617 area code — Boston, MA geographic

Data: NANPA public reports, current as of July 28, 2026.

617 is the area code for Boston, Massachusetts, in service since January 1, 1947, Eastern time. It is part of the 617/857 overlay complex — these codes share the same territory. Note that porting and VoIP mean a 617 number can be used from anywhere — the code marks where the number was assigned.

768 central-office prefixes are currently active in this code, spread across 24 code-holding carriers. Thousands-block pooling applies to 401 prefixes, so a single prefix can belong to several carriers. Its prefixes map to 27 distinct rate centers.

To check where a specific 617 number was issued, look up its six-digit prefix; to check who is actually calling, ignore the display and verify through an official callback number — caller ID is assertable and routinely spoofed.

Dialing: 10D locally, 10D to other codes (1+10 digit permissible at service provider discretion).

NANPA projects numbering capacity for the 617/857 complex to exhaust in 3Q 2066.

It has since spawned 508 (1988), 781 (1997), 857 (2001).

Largest localities in 617

FAQ

Is 617 a toll-free number?

No. 617 is a geographic code; calls are billed like any other domestic call. Toll-free codes are 800, 833, 844, 855, 866, 877 and 888.

Why do 857 and 617 cover the same place?

They are overlays: when a code runs low on numbers, a new code is added over the same territory instead of splitting it. The 617/857 complex shares one service area, and local calls are dialed with 10 digits.

Will 617 run out of numbers?

NANPA's current forecast projects exhaust in 3Q 2066 — decades of capacity remain.

Why am I getting spam calls from 617 numbers?

Scammers spoof recognizable area codes so calls look local or familiar. A displayed 617 number does not prove the call originated there — see our guide to spotting spoofed calls.