Patton TDU-4000-R - Telephone disconnect unit for Phone, Fax, Data, STU and STE equipment, 0-56 Kb, one line interface, one inst
by PATTON

The Patton Model TDU-4000-R provides protection for phones from being used as clandestine listening devices by electrically disconnecting the telephone line from the phone when the phone is in the “on hook” position.

During disconnect the telephone line is left open, while the voice path on the phone is grounded. This disables room audio from being transmitted onto the telephone line to prevent any eavesdropping. The phone will only connect to the telephone line when it is in the “off hook” position. The “off hook” detect and “ring” detect signals are also opto-isolated from the phone.

The TDU-4000 is part of the FOI line of products designed for ruggedized MIL applications. It is housed in the familiar FOI shielded enclosure. For standalone applications it can be powered by adding a PSQ-3909 AC supply or a PSQ-3920 DC power supply (not included). Optionally, up to 8 units can be mounted on CMA chassis adapters and installed in an RMC-3101 rack mount chassis.