Armed with just a number and a few hundred dollars, a bounty hunter can find the current location of most phones in the United States, according to an alarming new report by Motherboard. The tracking tool used by bounty hunters relies on real-time location data that’s sold to them. The data ultimately originates from the telephone companies themselves, including T-Mobile, AT&T, and Sprint. Law-enforcement agencies can only track phones with a warrant to service providers or via companies that sell location data. However, at least one company, called Microbilt, is selling phone geolocation services with little oversight to several different private industries, including bounty hunters, according to Motherboard. The lack of oversight shows just how exposed mobile networks and the data they generate are, leaving them open to surveillance by ordinary citizens, stalkers, and criminals.