Question About Radio In Locomotive

Correct the railroad uses base stations controlled by Phone lines.
The Dispatcher just selects what area he wants to talk too.

actually they use frame relays to control them and they are voip data over a 56k frame relay, with analog PSTN as an emergency backup

There are times I can hear TDD's and traffic up to 60-100 miles away in the cab of the P42's. This is mostly along the side of the mountain passes we travel over or the wide open stretches of desert in Utah and Nevada.

As some have mentioned, we can typically hear other traffic 10-20 miles away and that is enough. Too much traffic wears on you when it does not pertain to your operation and your having to listen while operating to determine if that radio call is for you or someone else.