Ahh, that takes me back!
In the UK there was a VHF mobile phone system called 'System 4'
Worked near the VHF marine band.
One of the phones i had (Storno 5000) has a 50W amplifier in it and drew close on 20Amps at 12V when used!
Not surprisingly you had to have the engine running to make a call!
The system was switched off in the early 80's when cellular took over.
How technology moves on.
The Storno was about £5000 to buy, most people rented.