Welcome to the DOD TSSI/DSN Website!
The Telecom Switched Services Interoperability (TSSI) Program
includes interoperability certification of DOD's voice, video, and data services across the circuit switched
network. The circuit switched network comprises the Defense Switched Network (DSN) and customer premise
equipment (CPE). As approved by Office of the Secretary of Defense (OSD), the DSN, is an interbase, nonsecure
or secure Command & Control (C2) telecommunications system that provides end-to-end command use and
dedicated telephone service, voice-band data, and dial-up video teleconferencing (VTC) for C2 and non-C2 DOD
authorized users in accordance with national security directives. Non-secure dial-up voice (telephone) service
is the system's principal requirement.
