This is an excellent example of how large corporations can't plan products normally any longer. You could take a college class in embedded systems design and you could ask all the students to come up with examples of edge cases where an SOS system in a car could have issues, and you're pretty much guaranteed that someone will mention both being out of range of cell towers and being old enough to be incompatible with cell towers.
Discussion would then lead to what to do about it, and busy-waiting in a loop trying to contact cell towers again and again would certainly not be a solution.
But can a corporation do this? Apparently not. I honestly wonder if designers are actively discouraged from caring about anything beyond the projected life of a product, because it could negatively impact later sales.