Area Code 617 — Boston, Massachusetts

NANP area code

617

UTC−5, UTC−4 during daylight saving

State
Massachusetts
Primary city
Boston
Time zone
Eastern
In service
1947
Overlay
857

The code reaches 74 communities and 6 counties across Massachusetts.

Was this call legitimate?

The area code itself carries no risk signal. 617 is assigned to Boston, Massachusetts, so a call from it is consistent with a real caller in that area — but the digits alone prove nothing, because they can be forged.

Caller ID is set by whoever places the call, not verified by the network. That is why neighbour spoofing works: an operation anywhere in the world can display a number that matches the area code — and often the first three digits after it — of the person being called, so the call looks local. Every community in the 617 territory is a plausible-looking origin for a forged 617 number, which is why one can be made to look like a neighbour to so many people. The same applies to its overlay code 857, which serves the same ground.

If you did not recognise the call: let it go to voicemail — a legitimate caller with real business will leave one. Do not return the call using the number shown; look the organisation up independently and call the number you found. Never confirm personal details, card numbers, or one-time codes to someone who called you, however plausible the number looked.

Codes.zone publishes no complaint counts, risk scores, or caller identities. We hold no data on individual numbers and will not estimate what we cannot source.

Local time and when to call back

Time there now

Eastern · UTC−5, UTC−4 during daylight saving

Reasonable callback window

8:00 AM – 9:00 PM

local time in Eastern

Federal rules bar telemarketing calls to a residence outside 8:00 AM–9:00 PM in the called party's own time zone. It is a sensible bound for a personal callback too — and a caller who rang you well outside it was not observing it.

Overlay codes and ten-digit dialling

617 does not have its territory to itself. 857 covers the same ground, serving Boston and the rest of the 617 territory. An overlay is what a regulator adds when a region runs out of assignable numbers: rather than splitting the area and forcing half the residents to change their number, a second code is laid over the top and new numbers are issued from it.

The practical consequence: two neighbours on the same street can hold numbers in different area codes, so the code tells you nothing about which part of town a caller is in — and local calls must be dialled as all ten digits, because seven is no longer unambiguous.

Cities served

largest 20 by ZIP count
Communities served by area code 617, ranked by how many ZIP codes each holds.
CityZIP codesCounty
Boston36Middlesex County
Cambridge6Middlesex County
Lynn6Essex County
Andover5Essex County
Quincy4Norfolk County
Waltham4Middlesex County
Dorchester3Suffolk County
Plymouth3Plymouth County
Somerville3Middlesex County
Watertown3Middlesex County
Arlington2Middlesex County
Braintree2Norfolk County
Brookline2Norfolk County
Burlington2Middlesex County
Dedham2Norfolk County
Hanover2Plymouth County
Hingham2Plymouth County
Lexington2Middlesex County
Medford2Middlesex County
Allston1Suffolk County

54 further communities not listed. All Massachusetts area codes →

Each point is a community served by 617, plotted from its record coordinates. The outline is the convex envelope of those points — a footprint, not a boundary.
  • Reference points and footprint
  • Not an official NANPA boundary
  • Not a USPS delivery area

Scope every community matched to 617. Source geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot), GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated . Coordinates are place reference points, not boundaries.

Counties

Prefixes inside 617

We do not publish the NXX prefixes inside 617. The assignment of prefixes to rate centres comes from LERG routing data, which is proprietary, and we will not estimate it from postal data — ZIP codes and telephone prefixes do not map onto each other. Awaiting a clean-rights NPA-NXX source.

Why this code exists

617 has served this territory since 1947. It eventually ran short of exchanges to hand out, and rather than split the region and make half its residents change their number, the regulator laid 857 over the same ground in 2001. New lines here are issued from the newer code, which is why a neighbour’s number may not start with 617.