The lack of the GSM-R, especially seeing it included in original TS routes, subtracts a certain element of the realism. Perhaps to aid less experienced players, a tutorial on use for it could be added for them.
Can someone explain what GSM-R does in the game, from what I can see you type some numbers in and it then just displays a service number. Now if it could be integrated with the Tab menu that might serve a purpose - but probably best having it preset and you just press SIG to call the bobby.
The GSM-R registers your headcode with the signalbox of whichever areas you pass through. At the very start of the journey, you enter in the headcode and the signal you're starting against. For argument's sake, let's assume our headcode is 1A38 and our starting signal is VC 495. You'd enter in the GSM-R as follows: 1A38 495 > enter. Once it's calibrated then your route can be set and the starting signal will change accordingly. The GSM-R wouldn't be a HUGE addition, but certainly a very good touch of realism.
The only point of GSM-R in game would be to have something on the GSM-R screen other than a blank blue LED grid... Until they add in some form of "malfunction or signaller contact from signal box to train" mechanism it wouldn't do too much DTG have already started adding in the big red button functionality to call the signaller FYI - to register the GSM-R you click the register button, type in your headcode using the number keys, then the last three digits of your current viewed signal (or on a special board) and then click register again. The unit checks with the signal box and then if all good it registers. That's literally ALL it would be doing in game