If the drone were merely a relay allowing the user to make a call on a cell phone, I suspect that it would be used for non-emergency calls almost exclusively. This would be legal in many places like the Ozarks, but given the lack of Forest Service personnel to enforce current wilderness regulations, it would just present one more temptation for the hikers who think only of their own pleasure and convenience to proliferate drones where they don't belong, in order to feed their phone obsession.