The EJ-T injects 2-way telephone line audio into a PA Affordable system. Simply hook-up the EJ-T between the telephone outlet on the wall and the base of the phone, then make a connection between the output of the EJ-T and either a mic level input (requires 16-EJTM cable), or a line level input conection to a PA system. Active Circuitry The EJ-T provides an affordable solution for distance learning in the classroom, simple teleconferencing in a boardroom, or broadcasting a teleconferenced call over a PA system in an auditorium. The EJ-T can also be used as an interface to record a telephone conversation. Just connect the output to a recording device. The EJ-T is an active device, and comes with its’ own 9VDC power supply.