The numerical designator 339 identifies a specific geographic region within the North American Numbering Plan. This area code serves communities within the Commonwealth of Massachusetts, operating alongside the established 781 code as an overlay. As an overlay code, it serves the same geographic area as another established code. As an example, a phone number assigned under this code might look like 339-555-0100.
Its introduction became essential due to the increasing demand for telephone numbers in the region it serves. Implementing this new designation allowed for continued expansion of telecommunication services without requiring existing users to change their numbers. The historical context involves anticipating future needs within a rapidly growing technological landscape, where mobile devices and internet-based communication have become ubiquitous.