That would be my assessment. They all had an accident, with James witnessing the loss of his two friends. Hurt physically and mentally, on his call to his son, he didn't have the wits about him to make the hard task of informing them and came up with all he could at the moment, that one was in town and the other on a plane.
I figure he watched the other two fall while he was barely able to save himself. He ended up being hurt and alone, unable to make it down on his own.
I don't know if the other two had cell phones that worked, but that certainly would explain why they didn't use James's cell phone that did work.