The Clear-Com PIC4000B IFB Program Interrupt Controller contains audio and switching circuitry for selecting 1 of 2 program signals, routing the signals to 4 independent talent channels and interrupting, with variable program attenuation, the signals from 1 or more control points. This unit contains the circuitry for selecting one of two program sources, sending the program to the IFB channels, and interrupting it via the Talent Control Station.