AT&T dropping cellphone tracking codes

WASHINGTON – AT&T Mobility, the nation’s second-largest cellular provider, said Friday it’s no longer attaching hidden Internet tracking codes to data transmitted from its users’ smartphones. The practice made it nearly impossible to shield its subscribers’ identities online.

The change by AT&T essentially removes a hidden string of letters and numbers that are passed along to websites that a consumer visits. It can be used to track subscribers across the Internet, a lucrative data-mining opportunity for advertisers that could still reveal users’ identities based on their browsing habits.

Verizon Wireless, the country’s largest mobile firm, said Friday it still uses this type of tracking, known as “super cookies.” Verizon spokeswoman Debra Lewis said business and government customers don’t have the code inserted. There has been no evidence that Sprint and T-Mobile have used such codes.

“As with any program, we’re constantly evaluating, and this is no different,” Lewis said, adding that consumers can ask that their codes not be used for advertising tracking. But that still passes along the codes to websites, even if subscribers say they don’t want their data being used for marketing purposes.

The tracking codes are part of the latest plan by the cellular industry to keep tabs on users and their devices. While the codes don’t explicitly contain personal information, they’re unique and nonetheless sent to websites alongside personal details that a user may submit voluntarily – like a name or a phone number. That means enough data can transform a large chunk of random digits into a digital fingerprint that’s as identifying as a Social Security number.

AT&T said Friday its tracker was part of a testing project that’s been phased off of its network.

The magazines Wired and Forbes first reported last month that Verizon and AT&T were inserting the tracking numbers.