Cell phones (and more importantly) cellular networks were available in the US from the early ’80s.
Here’s a photo of a very popular cell phone from 1983, the Motorola Dynatac:
It’s pretty big. you probably remember it.
It was used mostly as a car phone, since the FCC limited its power outside of the car. If memory serves, the transmitter could be up to three watts in a car, but about 1/5 of that outside of a car.
They didn’t really become very popularly priced until the 90’s though.