It's always difficult to know what to believe. There is so much disinformation and there and conspiracy theorists. Some of it's just bat-shit crazy, but others do have roots in reality. This seems like something that I would consider "plausible." It's amazing what LEO does. They tracked that attempted bomber in Spokane on MLK day to an online racist forum.
On the comment a while back about the battery source to keep time, that seems right. I'm certified with computers and that's something computers have. There is a small battery source in computers for when there is no power and since smart phones are computers, they may have the same.
For now, I'm just an indoor guy, but if I ever go outdoors - I'd probably just stay on the safe side and take the battery out of my phone b/c I doubt that that small power source for the clock and such (if it exists) would be strong enough to send a signal.