The Automatic Voice Network (AUTOVON) was a world-wide American military telephone system. The system was built starting in 1963, based on the Army's existing Switch Communications Automated Network (SCAN) system. In June 1966 the Air Defense Command voice network was cut-over to the new service. In the mid to late 1960's, AUTOVON switching centers open in the United Kingdom, and later in other European countries, Asia, the Middle East, and Panama. It was a major part of the Defense Communications System (DCS), providing non-secure switched voice services. The system was replaced in the early 1990's by the Defense Switched Network.