Massachusetts · Eastern Time
Cambridge, MA Area Codes
Cambridge is served by 2 area codes (617, 857). Here's which is original, which are overlays, and how to pick one for a new local number.
Last updated October 3, 2026 · Source: NANPA
Area codes serving Cambridge
Cambridge sits in Massachusetts, part of the Northeast region and the Eastern Time zone. Its numbers are spread across an overlay of 2 codes that all cover the same ground: 617, 857.
The original code is 617 (in service since 1947). As the area ran low on numbers, regulators added overlay codes on top instead of splitting the city, so longtime residents kept their numbers while new lines received a newer code.
| Code | Area served | In service |
|---|---|---|
| 617 | Boston and its closest neighbors including Cambridge, Quincy and Newton | January 1, 1947 |
| 857 | Boston and its closest neighbors including Cambridge, Quincy and Newton | May 2, 2001 |
Nearby cities sharing these area codes
- Boston
- Quincy
- Newton
- Somerville
- Brookline
- Watertown
- Chelsea
- Everett
- Belmont
- Milton
- Winthrop
How to pick an area code for a new number
When you activate a new line in Cambridge, the carrier assigns whichever code has numbers available — you usually can't choose. If a specific code matters to you (for example the prestige of 617), ask the carrier whether any blocks remain, or request a number transfer. All codes here dial identically and cost the same.
Dialing in Cambridge
Because Cambridge is an overlay area, 10-digit dialing is mandatory: always dial the area code plus the seven-digit number, even for a neighbor. From outside the US, dial +1, then the area code and number. See 10-digit dialing and overlay area codes for the background. For every code in Massachusetts, visit the Massachusetts area codes page.
Quick answers
Cambridge area code FAQ
What area codes does Cambridge use?
Cambridge, MA is served by 2 area codes: 617, 857.
Which is the original Cambridge area code?
617 is the original code for Cambridge, in service since 1947; the others were added later for more numbers.
What time zone is Cambridge in?
Cambridge is in the Eastern Time zone.
Do I need to dial the area code in Cambridge?
Yes. With multiple overlapping codes, 10-digit dialing is required for every call in this area.