The audio in and out signals must be provided by other means within the facility. The pushbuttons illuminate when a call is received. The APC-88 also has a solid state relay that closes on incoming speech which may be used to trigger listen facilities. A good example would be a talkback input to a console cue speaker or monitor. The APC-88 is available in many different housings for most audio consoles.
Intercom provides built-in IFB capability.
A program source may be connected to any spare input and assigned using the central AXC-8R Control Panel. Multiple program sources may be mixed to a destination using the system administering terminal. The mix will then be automatically interrupted by talk activity. IFB destinations are typically outbound lines which do not require an input to the intercom matrix. This frees up input ports for program line input to the intercom matrix.