Basically, yes. In the olden days, cell phones sent a ping at least once a minute to the nearest tower, and sometimes more often. The tower would respond with a similar message. There was a 140 character field in the ping that could be used for a variety of diagnostics and network controls. That field was also used for text messaging and so was pretty much free for the providers, other than the very small amount of general network backhaul overhead of sending that message to another phone. Charging for texts was a hell of a rip off.
Basically, yes. In the olden days, cell phones sent a ping at least once a minute to the nearest tower, and sometimes more often. The tower would respond with a similar message. There was a 140 character field in the ping that could be used for a variety of diagnostics and network controls. That field was also used for text messaging and so was pretty much free for the providers, other than the very small amount of general network backhaul overhead of sending that message to another phone. Charging for texts was a hell of a rip off.