To be technically correct. The satellite aspect is only receiving from the GPS sats. No consumer devices send TO the satellites. The device data is sent via old-world 2G GPRS packets - relatively unused cellular function now that everything else is 3G/4G. A LOT of tracking and pay-as-you go insurance and driver mileage schemes use the same thing.
p.s. - the amateur radio APRS solution is 'free' for the 'service', one time cost of getting the license and about $200 worth of gear/antenna to setup. Once you have the license it's also a great way to have more on-road communications for local help.
p.p.s. - to another note, it is not legal or practical to try to send data over AM or SSB CB.
Enjoy the ride! Best 73!
de Jim, NO1PC