There is already a mod called ACRE which adds this type of functionality to an extent. http://forums.bistudio.com/showthread.php?133891-A-C-R-E-Advanced-Combat-Radio-Environment-1-4-Stable-Release-Thread It integrates with teamspeak and so those on the same TS channel have really good directional and distance based direct von and radios can be picked up tuned to a channel ect. You can also pick up enemy radios and the channel they were on will stay and so you could kill a bandit take his radio and listen to his friends. Its limited though in that you need teamspeak to make it work.
