>Systems need to be robust, interoperable, reliable, provably correct, fail safely, deal with surprising edge cases, have long service lives, and any number of other challenges.
Since many current systems do not meet those criteria (another comment mentions a “communication system” of writing down the day’s train drivers’ cell numbers on a note), I’d argue that any improvement towards an ideal system is a step up. We can’t wait for perfection.
Those steps up already exist. The railway I work for has in-cab radios that we routinely measure the signal coverage to confirm minimal black spots, plus there’s also GSM phones (as in, hardwired in the driver’s cab), in all our locos.
Since many current systems do not meet those criteria (another comment mentions a “communication system” of writing down the day’s train drivers’ cell numbers on a note), I’d argue that any improvement towards an ideal system is a step up. We can’t wait for perfection.