I assume, though nobody has said so, that there was no cell service in such a rugged area.
The cell phone angle is interesting in this case. Their cell phone never indicated that they had a signal but one distant tower registered them trying to connect. It took some sluthing but some techs found the attempt, determined the general area the attempt came from and told the searchers to check that area. That's how the helicopter found the car with the wife and kids.
