The DT-90 Is an audio switcher that is controlled by DTMF tones over a standard telephone line.
It features 4 mono channel inputs and one mono channel output. (Balanced in and out). There are also 4 relays and an internal microphone that can be controlled. The relays (DPDT) operate independently of the switcher. They can be programmed to operate momentarily, latching or interlocking. The built in mic allows you to call the unit and listen for sound where the DT-90 is located. All connections are made via convenient plug-in terminal strips.