That answers something I've wondered about for a long time. I remember the days long before cell phones and some people did have phones in their cars. It was mostly important people in Limos..Plate Cap wrote:My first mobile telephone, in 1978 or so, was UHF (454-459 MHz) system, first operating on Michigan Bell's IMTS system, then later on RAM Broadcasting's system.Fingerboard Corners wrote: Then they made it illegal to listen to cell phones, whereas portable phones were legal to listen to and you had a good idea on who it might be close by on those.
Listening to the other users was easy; there were only 12 channels on each system. Some very, very interesting conversations went on....I knew someone who often drove with me, and when I was out of the car on errands, he would amuse himself by listening. He even got to know the personality of a few other users, from listening so much. There were some movers and shakers, and they had no clue on earth their calls were essentially public.
If you are doing the math in your head, you're right....24 simultaneous conversations on UHF, and another 13 on VHF....the 28th person in southeast Michigan trying to make mobile call couldn't.
Cellular didn't come into viable use in the area until about 1981 or so; I get a kick out of the 'kids' at the Verizon store that think mobile telephony started with cellular bag phones. It was a difficult transition from IMTS to cellular, as the cellular build out was rather slow.
The forerunner to what is now Verizon here, "Detroit Cellular Telephone Company" was especially slow to build out, choosing tall sites (and therefore not a lot of channel reuse) and ended up suing and winning the right to place their customers on Ameritech's system, pretending all the while the service was coming from them.
Was the range on those devices limited to line of sight from a single tower?