During the mid-1960s, the United States Government decided to implement a worldwide secure voice network. This was named Automatic Secure Voice Communications Network, or by its acronym AUTOSEVOCOM, and was the
National Security Agency's first program for the
United States Department of Defense's telephone protection. It was a cumbersome and expensive system that was available only for high-level users. Because of its inadequacies, the Defense Department capped it at 1850 terminals, and in the late 1960s, hoping for something better, decided not to continue with the expansion of AUTOSEVOCOM. Phase I of the network was approved by the Deputy Secretary of Defense in July 1967 and after that it took several years to implement AUTOSEVOCOM within the continental United States. AUTOSEVOCOM-I was a non-tactical network that enabled users to discuss classified or sensitive information over the telephone. The network consisted of switching centres, transmission facilities and subscriber terminals. Subscribers were homed either on an AUTOSEVOCOM switch, on an Automatic Voice Network (AUTOVON) switch, or a Joint Overseas Switchboard (JOSS), which were for example operated and maintained by numerous Signal Battalions in Vietnam. The AUTOSEVOCOM switches provided for wideband secure voice communications between local subscribers and enabled them to establish long-distance secure voice calls. The majority of the long-distance calls were routed by the AUTOVON. == Phase II ==