Area code 339 is an overlay of 781 and serves the suburbs just outside of Boston, Massachusetts, including Waltham, Medford, Quincy, and Lynn. It was introduced in 2001 to accommodate increasing demand for phone numbers in the greater Boston area. Ten-digit dialing is mandatory. The 339 region includes a mix of historic towns, affluent suburbs, and coastal communities. While 781 is the more established code, 339 has steadily grown in usage and acceptance. It reflects the Boston metro area’s expanding influence and connectivity, especially in technology, education, and health industries.