eli5 : how did the car phones from 80s and 90s movies work?
They worked basically like the cell phones of today: They transmitted and received a radio signal from a nearby tower which carried the call through land lines into the normal telephone network. The difference though is that the earlier electronics were very bulky and required a big box of equipment along with usually an external antenna which could be affixed to the outside of the car magnetically. They also transmitted and received with much more power so you really didn’t want the antenna to be right next to you.
Your modern cell phone is a marvel of miniaturization and can cram all the capabilities of those car phones plus much more into a smaller form.
The first car phones were around in the mid 1940s, and they worked the same way your modern phone works. It transmits over radio to a tower.
Here’s a film from the 1940s showing how mobile telephones work. https://youtu.be/xDy2tHCPdk8
Car phones worked on cellular technology, the same way as modern cell phones. That’s not a long enough answer so I’ll just say they usually were very expensive and had a speakerphone system installed by default with the option to pick up the receiver and hold it like an old fashioned phone. My dad had one for years before it became obsolete by just having a cell phone. He liked it for the quality of the speakerphone system versus cellphones at the time. He could also get good reception with bigger antennas installed directly on the car.