An online advertising clearinghouse relied on by Google, Yahoo and Facebook is using controversial cookies that come back from the dead to track the web surfing of Verizon customers.
The company, called Turn, is taking advantage of a hidden undeletable number that Verizon uses to monitor customers' habits on their smartphones and tablets. Turn uses the Verizon number to respawn tracking cookies that users have deleted.
Does Your Phone Company Track You? Check for Tracking Code. Click from your smartphone or tablet (with Wi-Fi turned off) to see if your telecom provider is adding a tracking number.
"We are trying to use the most persistent identifier that we can in order to do what we do," Max Ochoa, Turn's chief privacy officer, told ProPublica.
Users complained that the tracking number could be used by any website they visited from their phone to build a dossier about their behavior – what sites they went to, what apps they used.