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The primary function of the DSN is to provide non-secure voice service. The DSN provides rapid, reliable, survivable, non-secure/secure, and economical C2 telecommunications. To take advantage of economies of scale, the DSN also provides service to non-C2 users on a not-to-interfere basis.

The DSN system is used only for official business or in the interest of the government and is the first choice for all switched voice and dial-up video telecommunications between DOD user locations.

DSN Requirements – The DSN must adhere to these capability objectives:

  • Survivable Service
  • Assured Connectivity
  • Responsive Service
  • Surge Capacity
  • Secure Service
  • Interoperable Service
  • National Security/Emergency Preparedness (NS/EP) Compliant Service

The Defense Switched Network (DSN) is a primary information transfer network for the Defense Information System Network (DISN). The DSN provides the world-wide non-secure voice, secure voice, data, facsimile, and video teleconferencing services for DOD Command and Control (C2) elements, their supporting activities engaged in logistics, personnel, engineering, and intelligence, as well as other federal agencies.
In 1982, the DSN was designated by the Office of the Secretary of Defense and the Joint Chiefs of Staff (JCS) as the provider of long-distance communications service for the DOD. The DSN is designated as a primary system of communication during peacetime, periods of crisis, pre-attack, non-nuclear, and post-attack phases of war. The network assures non-blocking service for users with flash and flash override precedence capabilities. Key users include the National Command Authorities, Combatant Commanders of the Unified Commands, and strategic and tactical subordinate commanders.

The DSN consists of four subsystems: Switching, Transmission, Timing and Synchronization, and Network Administration and Management. The DSN Switching Subsystem consists of multifunction, stand-alone tandem, end office, and remote switching units. Using the transmission, timing, and control elements of the DISN, they interconnect all military locations world-wide and provide end-to-end long-distance common user and dedicated voice, secure voice, data, and video services world-wide.

In addition to non-secure voice, data, and video services, the DSN provides transmission, switching, and support services for the secure terminal equipment STE), the Defense RED Switch Network (DRSN), dial-up alternative routing for the Unclassified but Sensitive Internet Protocol (IP) Router Network (NIPRNet), and the Secret IP Router Network (SIPRNet). The DSN also provides access to the Government Emergency Telephone System (GETS).