For when we have a human controlling forces, being AWACS or CGI, and functioning as the overall overlord.
On radio, callsign is "Overlord". In addition to guiding planes, you'll also schedule new outbound flights, organize players who just returned from tasking, etc etc etc.
How to set up IVC
You need some fiddling to use IVC from map screen to talk on radio channels.
F4AWACS as software, and every client should run the supporting software.
Interactive map of Korea for giving TACANs, radio channels, and whatever needed assistance to planes looking for alternative fields etc etc. http://www.combatsimchecklist.net/MAPKOREA/