The UP dispatcher's console connects to any number of remotely controlled radio base stations in the field by point-to-point microwave, dedicated phone circuits, radio links, or a combination of any of the three. Unless a dispatcher has chosen to be monitoring a base station at his console, all receiving is muted to him so as to not be overwhelmed by trying to listen to them all at once. When a train or mobile wants to call him, they enter a pre-designated touch tone code for the area they are in. If the nearest base radio receives the request, it sends back an acknowledgement tone. On the dispatcher's console in Omaha (actually all UP lines in Texas are dispatched from Spring north of Houston) the icon for that base station starts to blink on their computer monitor, and the dispatcher answers when they are able. If the dispatcher wishes to initiate a conversation, they merely clhoose the icon on their screen for the nearest base station, and verbally calls for the train or mobile. Does this help?