AT&T ends tracking of customers by "supercookie"

SAN FRANCISCO - AT&T has ended a controversial program that used hidden "super cookies" to track smart phone users as they surfed the web.

The program added a hidden and undeletable tracking number into all the Web traffic on a users' cell phone.

The news site ProPublic reported Friday that AT&T had ended the practice.

Verizon Wireless, the country's largest mobile firm, said Friday it still uses this type of tracking. There has been no evidence that Sprint and T-Mobile have used such codes.

The AT&T codes used to track cell phone users' web surfing only become public in late October.

The unique identifier code marks each website a subscriber visits. This allows the company--and advertisers--to build up a profile of everything the subscriber does online, by following the trail of sites he or she has visited.

"We have completed testing of the numeric code that would be part of any new mobile Relevant Advertising program we may launch," said AT&T spokeswoman Emily Edmonds..

If AT&T launches any new programs, customers would still be able to opt out of the ad program "and not have the numeric code inserted on their device. Customer trust is important to us, and customers have choices about how we use their information," she said.

Edmonds said customers had also had the option to opt-out of the testing period of the program.

However during the testing phase, customers were not informed they were being tracked so it is unclear how they would have known to do so.

The tracking of people using their smart phones to surf the web is of concern because for many they have become people's "second brain," said Jacob Hoffman-Andrews, a senior staff technologist with the Electronic Frontier Foundation in San Francisco.

"If you have a question or you're wondering about something, pretty soon you're typing it into a web browser on your phone to answer it. You don't want everything that goes through your mind being indexed by advertisers and used to sell things to you later," he said.

Hoffman-Andrews said it was believed the program had been in place for about a year but in an email, Edmonds said that was inaccurate, but that AT&T was not releasing details about low long it had been going on.

AT&T said the change came because its period of testing was completed. Others believe the intense public outcry when the tracking was revealed led to the shift.

"AT&T is reacting to consumer pressure and they're now doing the right thing," said Rob Shavell, CEO of Abine, an online privacy company.

Verizon should note that too, he said.

"If companies like Verizon continue to ignore consumers' rights to privacy and choice in how their information is able to be accessed, they'll be subject to hugely increased government regulation," Shavell said.

Verizon spokeswoman Debra Lewis told the Associated Press that business and government customers don't have the code inserted, only consumers.

"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.

Cryptographer Kenn White has created a website where users can see if their phone is tracking them.

Contributing: AP