[jasonwatkinspdx]

Two way pagers have been a thing since the 90s. You're limited to replying with a very short alphanumeric message.

That said, pagers don't continuously ping the tower like cell phones do. They can stay receive only until the moment you chose to send a message.

[BuildTheRobots]

The AR924's in question are POCSAG pagers; broadcast from base stations and receive only at the pager end. Two way pagers are a thing but use an entirely different protocol for communications.