https://motherboard.vice.com/en_us/article/d3mzz7/cyber-podcast-episode-bounty-hunters-location-data

Recently, Motherboard sent $300 to a bounty hunter. Shortly after, he sent us a Google Maps screenshot with the real-time location data of a phone that we'd asked him to track.

This tracking wasn’t thanks to a fancy hacking technique or spy device: it was thanks to data collected and sold by the telecom companies themselves, including AT&T, Sprint, and T-Mobile.