Short answer is almost no one has cell signal and there are no wifi hot spots. You are disconnected if you are in the canyon.
The only carrier that seemed to have occasional signal was AT&T.
Driving to the top and finding signal was our only option.
And as good as Mrs Ram’s iPhone has been in the past, is it some how struggled here. Mr Ram had found a great spot on the top if the canyon with nearly 5 bars of signal while Mrs Ram had none. We ended up parked in the grass on the side of busy Texas two lane ti get signal for both of us.