The 857 area code is located in the state of Massachusetts, and according to Intelius data, covers roughly 113,098 phone numbers and 131,901 listings across 361 prefixes.
This is a General Purpose Code, in service since May 2, 2001.
Area code 857 is part of an overlay complex shared with:
Area code 857 was split from area code 617.
Local calls within area code 857 require 10 digits dialing, while long-distance calls require 1 plus 10 digits dialing.
Have you received a call from a number with a 857 area code? Figure out who is calling you by performing a reverse phone lookup search. Intelius can provide you with a phone report that includes (when available) original line type and carrier, the number owner’s name, last known address and past addresses, age, possible relatives, and more.
| County Population (2025) | 1,669,979 |
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| County Population (2025) | 739,749 |
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| County Population (2025) | 791,891 |
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