What is what area code is 857?

Area code 857 is a telephone area code serving the eastern portion of Massachusetts, specifically the same geographic area as area code 617. It is an overlay area code, meaning that it does not have its own dedicated geographic territory but rather is assigned to the same region already served by another area code. This was done because the 617 area code was running out of available phone numbers. It covers Boston and surrounding communities. When dialing numbers within the 617/857 area, ten-digit%20dialing is required.