Area code 339 is an overlay for area code 781 in eastern Massachusetts, covering the suburbs surrounding Boston, including Waltham, Quincy, Lynn, and Braintree. It was introduced in 2001 to address the growing demand for new phone numbers in the Greater Boston area. With 781 already heavily assigned, 339 provided a seamless solution for expansion without requiring geographic splits. Ten-digit dialing is required across the entire 781/339 region. While 781 carries more historical significance, 339 has become increasingly common for mobile phones and new businesses. The area continues to be a major hub for residential growth, commerce, and high-tech industry in eastern Massachusetts.