I used to sell mobile phones in the mid 90s, phones like the nokia 100, and nokia 101. These phones were analogue, I think it used frequency modulation. Anyway in the same shop we had radio scanners too, and we could listen in on peoples random conversations.

Luckily digital phones arrived (gsm) and then we could no longer just listen in to random conversations. It's quite frightening that people had no idea anyone with a radio scanner could eves drop on their call. I remember one of the popular phones at the time was a nokia 8110, also known as the banana phone popularised by the matrix.

Anyway as you said, technology is constantly changing and normally for the better. I wonder what innovations lie ahead.