The system which does not allow the drivers to talk to each other realizes this by using different transmitting frequencies between the dispatch control center (base station) and the drivers (mobile stations) (a kind of semi-duplex operation).
会話できないものは、配車係（基地局）の送信周波数と乗務員（移動局）の送信周波数を変えることで実現している（一種の半複信方式）。