Your cell phone documents where you are every seven seconds

Your cell phone keeps very precise information on where you are every seven seconds. That is a little concerning. I suppose that it can be used to solve crime, but it can also be used for other less desirable things too.

But as a German Green party politician, Malte Spitz, recently learned, we are already continually being tracked whether we volunteer to be or not. Cellphone companies do not typically divulge how much information they collect, so Mr. Spitz went to court to find out exactly what his cellphone company, Deutsche Telekom, knew about his whereabouts.

The results were astounding. In a six-month period — from Aug 31, 2009, to Feb. 28, 2010, Deutsche Telekom had recorded and saved his longitude and latitude coordinates more than 35,000 times. It traced him from a train on the way to Erlangen at the start through to that last night, when he was home in Berlin. . . .

“We are all walking around with little tags, and our tag has a phone number associated with it, who we called and what we do with the phone,” said Sarah E. Williams, an expert on graphic information at Columbia University’s architecture school. “We don’t even know we are giving up that data.”

Tracking a customer’s whereabouts is part and parcel of what phone companies do for a living. Every seven seconds or so, the phone company of someone with a working cellphone is determining the nearest tower, so as to most efficiently route calls. And for billing reasons, they track where the call is coming from and how long it has lasted. . . .