The engine control computer in your car was mandated by federal law to ALWAYS maintain an open channel to the cell phone network in all makes and models of vehicles sold in America after 2004. Onstar equipped vehicles had it a lot sooner. The purpose for having this cell connection mandated in all cars sold during and after 2005 was to make it possible to listen to everything said in a car. And you can’t get rid of it, because the engine control computer is needed to make the car run. Two way communication would be possible in all of these cars if you were allowed to use that cell connection for your own purposes. But it is not there for you.
This is something I have known about for years, and I have advised my friends into the best possible (now older) cars that do not have this feature.
And there is a far more sinister side to this. It is possible to use that cell connection to reprogram the engine computer in any of these cars, and there is no safeguard in place to prevent cars from being reprogrammed to accept remote driving commands. It is being hypothesized now that it has become an assassination weapon, where air bags are set off to disorient or knock out the driver (and subsequently eliminate their protective ability), disable the brakes and steering, and floor the accelerator until the car crashes. A majority of cars nowadays are at least partially drive by wire, there is no mechanical linkage for many of the driving commands.
Read about it here: Was Arizona Sheriff Larry Dever Killed by Boston Brakes?