We have actually come quite a long way, I remember in 1979 if you wanted to get a clearance for a VFR helicopter to transit the Richmond control zone you would actually have to phone first on a land line for approval.
One day I was flying my aircraft and decided to divert to John Singleton’s horse stud, which was on the Nepean River just inside the Richmond zone. I called up the tower and asked if I could have a clearance and explained that this was a flight plan change. The controller explained that there was simply no way he could give the clearance by radio and that I would have to telephone. I then said, “well do you object if I land here at a homestead on the other side of the Nepean River and phone from there”, he said “no”, duly I made the phone call and got the clearance to fly in. I then managed to purchase one of the first brief case sized “007” mobile phones and put it in the helicopter, I was then able to phone up by telephone to get a clearance through the zone. Within months they realised I had outfoxed them and decided that you could actually call by radio in future to get a clearance. At last we were moving into the 19th Century.