Secure Digital Voice Terminal

The secure digital voice terminal (sdvt) is a four-wire non-secure/secure telephone set that transmits and receives digital voice and loop signaling information at 16 or 32 kb/s rates. the sdvt is a secure telephone that has embedded exportable encryption module capability that supports non-secure and secure (non-encrypted/encrytped) operations. the sdvt interfaces from up to 4 km away from the circuit switch to telegraph, facsimile, or digital voice by a 4-wire interface. the sdvt supports one active interface mode of operation at a time. the sdvt interfaces analog voice by the handset interface and to data devices by the rs-232 data port interface. the sdvt keyboard/keypad is used to enter address, precedance and other control information necessary for the sdvt user to establish a call.