It doesn't depend on what class you are, the fact is that proper radio usage is a random factor. However, since almost every class is available to to use it, it's pointeless, in my opinion, having state trooper as an exception. A trial look, as Tut correctly stated, would be a good start. On the other hand, if keep less public permissions like the radio one, players get bigger motivation to aim for PC and as result there's better individual future progress based on RPing and professionalism.