Reach Out and Track Someone

Your mobile phone lets companies and the government know where you are, even when you're not making a call.

Most people know that when they make a mobile call--during a 911 emergency, for example--authorities can access phone company technology to pin down their location, sometimes to within a few feet.

A lesser-known fact: Cell phone companies can locate you any time you are in range of a tower and your phone is on. Cell phones are designed to work either with global positioning satellites or through "pings" that allow towers to triangulate and pinpoint signals. Any time your phone "sees" a tower, it pings it.

That is what happened last month when a New York City murder highlighted the existence of the built-in capability of phones to locate people even when they aren't making calls.