Is Your Cell Phone Exposing Where You Are?

A phone with an built-in GPS system on view on the second day of the 3GSM congress in Barcelona,13 February 2007.
Larry Magid analyzes technology issues and devices for CBS News and

Imagine a world where you can be tracked anywhere you go. A decade ago that would have seemed like a paranoid delusion, but thanks to GPS-enabled cell phones and other technologies, it's more or less the way things now are.

Many of today's cell phones are equipped with global positioning systems that are capable of pinpointing your exact position. Soon, thanks to Federal Communications Commission (FCC) rules, all phones will be able to transmit your location. The question isn't whether you can be found, but how that information will be used and who will have access to it.

The FCC's Wireless 911 rules require that all U.S. cell phones be equipped with a global positioning system (GPS) or other technology so that emergency personnel can locate people who call 911 from their mobile phone. When the system is fully implemented, 911 operators will know your longitude and latitude, which is a good thing if you need help and can't report your exact location.

But there's nothing in the rules that say that the technology can only be used for emergency services. In fact, there are numerous commercial services that are already piggybacking on this E911 location technology. And it's not just cell phones that can track your location. Laptop PCs, PDAs, Internet phones and other WiFi (wireless networking)-enabled devices can also be used to locate you, thanks to a company that's mapped out the location of millions of wireless Internet adapters around the US.

While there are benefits to these technologies, there are also dangers. It's a bit scary to think about what could happen if these technologies were misused by stalkers, pedophiles, jealous spouses, nosy employers or overzealous government agents.

Location-based services (LBS) represent at least a $750 million market in 2007, according to David H. Williams, publisher of LBS Williams expects that market to grow by 75 to 100 percent in the next two years. In addition to emergency 911, LBS services include fleet tracking, navigation, child finding, local search, self-guided tours, finding lost elderly people and "social mapping."

Social mapping allows people to use their cell phones and PCs to broadcast their location so others can find them. So far there are only a few companies in the cell phone social mapping business including Loopt and Helio. (Disclosure: Loopt is one of several sponsors of a non-profit social networking safety project I work with called

Loopt, which is based in Palo Alto, Calif., offers a service on the Boost Mobile cellular network that allows users of these prepaid phones to locate their friends on a map that appears on their cell phone screen. There are now about 150,000 users on the Boost service, according to Loopt Vice President Mark Jacobstein. But Loopt is slated to grow and will soon launch with several major carriers.

Here's how it works. All phones that work with Loopt are equipped with GPS and other technologies that plot the user's position. If the phone has a clear line-of-site view of the sky, the GPS sensors can get signals from three or more of the 24 GPS satellites in orbit. If it's being used indoors or where there isn't a clear view of the sky, the phone, with the aid of servers located at Loopt, tries to calculate the user's position based on its proximity to one or more cell phone "towers" or antennas. If the phone can connect to one antenna, it can calculate a very rough approximation of the user's position to within a few miles. If it gets a signal from two antennas, it can hone in much further, but if it's in touch with three or more cell sites it can plot almost the exact location by measuring the distance from each site and using a process known as "triangulation" to find the users within a pretty close range.

Once the phone knows the user's location, it uses the phone's data channel to transmit that data to Loopt's servers. Then other Loopt users who have your permission to find you can see your location on their cell phone screen or on the Web.

The service can also be configured to issue an alert to find friends that are nearby, so you could, for example, be notified if a friend is within, say, a half mile of you. Likewise you can send out an invitation to all friends within a specified radius to join you at a bar or restaurant.

It doesn't take a great deal of imagination to think about how a service like this could be misused. There is also the issue of "Big Brother," whether that is the government or an employer who could use the technology to know the location of anyone with a company-issued phone, even when they're off duty.

Loopt is strictly a permission-based service, so for someone to track you, you must enter their phone number and you can withdraw or suspend that permission at any time. Also, you can only invite people whose phone number you know — you can't browse for "friends" as you can with some social networks. And, if someone does abuse the service, there is an electronic evidence trail that includes their phone number. Finally, Jacobstein said that Loopt deletes a users' location information as soon as they move to a new location, so there is no history of their whereabouts that could get into the hands of a hacker or even a law enforcement agency or an attorney with a subpoena or a warrant.

Helio, which is something of a boutique cell phone company, offers its customers a similar service called "Buddy Beacon." As an extra safety feature, Helio doesn't allow tracking. Users must beam their location each time they want someone to know where they are.