A group of students from Harvard used a weather balloon to send a sony camcorder, a gopro and a samsung phone 30 kilometers into the atmosphere to take pictures of the grand canyon. They planned on using the phone's GPS unit to locate the phone after its return to Earth. But once it landed, there was no signal from the phone and it was never recovered. Until Two years later when an AT&T employee just happened to be hiking in the area and found it. It turned out that despite AT&T's coverage maps indicating full coverage in the landing area, it was in a dead zone.
One of the students posted the story [reddit.com] along with gorgeous photos and videos over on Reddit.