CDI-17 is mission instrument consists of a Digital Audio Processor (DAP) module connected with a PC running GT user interface. The PC does not need to be dedicated strictly for use as an end instrument, it can run other applications such as the CONTEX system administration and maintenance client at the same time. A 17-inch touchscreen or mouse-driven monitor provides access to line keys and function buttons. Tapping or clicking a line key selects an audio circuit. Tapping or clicking a function button activates an advanced function such as conference focus, conference broadcast, or conference join.