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Upset about the National Security Agency's call record collection?

If you're a mobile phone user, you may have more cause for concern than the average landline user. Turns out, mobile phone records can reveal not only who you called, but location technology onboard the mobile phone and at the carrier network can reveal where you made the call and everywhere else you went too.

And if U.S. mobile carriers are handing over cellular location information to the NSA, that would allow the agency to map subscriber movements to a relatively accurate degree, say some security experts.

The reports of operators passing on call records have already caused widespread debates in the U.S. and the rest of the world about privacy and security interests. (See Poll: In Osama We Trust? and Online Groups Reveal Details of NSA Surveillance.) Ira Winkler, president and acting CEO of the Internet Security Advisors Group (ISAG), and a former NSA analyst, says that if the carriers are already passing on confidential details without a warrant, then they could just as easily be handing over subscriber location information.

"The fact of the matter is, if they're handing over call records, there's nothing to stop the hand over of that material as well," says Winkler. "It would be okay if they were to get warrants for it. There's nothing to stop people if they're not going to put limits on it."

Cingular Wireless LLC, the largest wireless carrier in the U.S., says that it doesn't just hand over information "willy-nilly" but will pass on information if the government makes a proper request.

"We comply with any government request as long as it goes through the correct channels," says a spokesman for the operator.

Roger Entner, VP of Telecoms at research firm Ovum, takes a slightly different tack. He argues that it is "theoretically possible" for carriers to keep track of subscribers. He cites cases where police have used carrier records to place suspects at the scene of the crime when they made a call on their mobile phone.

"We do it with the police as long as they have a warrant," the Cingular spokesman concurs.

Entner, however, doesn't believe that this is what the NSA is doing. "Under the inquiry from the NSA, no," he says.

Sprint Nextel Corp. and Verizon Wireless did not return calls about this issue.

Carriers are required to try and keep real-time track of users on their network by the FCC under the E911 mandate. This is so emergency services can find injured parties and other victims if they need to.

Two main technologies are used to track users. Satellite-based GPS tracking can be used with phones that have the chips installed. As Farpoint Group analyst Craig Mathias points out, however, operators don't need GPS to track a phone. "Since the handset is seen by multiple cells simultaneously, it's a small matter of software to triangulate and even track the signal," he tells Unstrung.

The accuracy of GPS tracking depends very much on the device having clear lines of sight to the sky, but in built-up areas carriers can combine cell-site triangulation with the satellite data to get a more accurate picture. The FCC mandate calls for the phones to be able to locate cell phones to a point within 100 yards. GPS users with whom Unstrung has spoken say that the satellite is typically able to locate a transceiver to a city block but not with pinpoint accuracy.

It is also not clear at this point how long operators keep records of customer location details.

— Dan Jones, Site Editor, Unstrung. Special to Dark Reading.

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