Boston, MA is utilizing an area code overlay in which area codes 617 and 857 serve the same geographic area. The area code overlay was put into service on May 02, 2001 at which time area code 857 was created as an overlay of area code 617. Area code 617 was put into service in 1947 and was one of two original area codes, 413 being the other, which served the entire state of Massachusetts until 1998 when area code 508 was created. Ten digit dialing (area code + seven digit number) is necessary because two different homes in the same geographic area can have the same seven digit phone number but each would have a different area code.
In addition to Boston, MA area codes 617 and 857 serve an area of east central Massachusetts, including Boston and the close suburbs of Boston. Some of the larger communities served by area codes 617 and 857, include Belmont, Brookline, Cambridge, Chelsea, Everett, Milton, Newton, Quincy, Somerville, Watertown and Winthrop in addition to many smaller communities within the service area.
Boston, MA is located in Suffolk County and observes the Eastern Time Zone. View our Times by Area Code tool.