Area code and exchange code is assigned to every constituent of city in the United States. The area and exchange codes of the telephone can be used to find information about a region. Area code 401 and exchange code 859 is assigned to Charlestown. The latitude and longitude corresponding to 41.17 and -71.56 can be used to find an area on the map. Pac-West Telecomm, Inc. - Rioperates most of the land lines in United States.