BT will kick off its public trial of the controversial Phorm ad-serving software tomorrow.
The move comes days after the City of London police dropped an investigation into the legality of two previous secret trials.
BT hopes to get 10,000 users to sign up to the trial, which it expects will last at least four weeks. BT said the delay in starting the trial, dubbed BT Webwise, originally expected in summer, was caused by to technical issues that were now resolved.
Phorm plans further trials with Virgin Media and Carphone Warehouse's TalkTalk after the BT trial ends. Phorm said it has had "a significant level of commercial interest" from other ISPs in the UK and abroad, as well as major agencies, publishers and ad networks.
"Following successful completion of these trials and an appropriate planning period, it is currently expected that Phorm's platform will be rolled-out across these networks, a Phorm spokesman said.
Civil liberties activists argue that Phorm and BT illegally collected and stored users' personal data. The data was used to develop "profiles" of users' interests in order to serve ads to them as they surfed the net.
The Information Commissioner's Office, the Department of Business Enterprise and Regulatory Reform and others have given Phorm the all-clear. A strict rules of conduct includes an explicit "opt-in" decision and to keep users anonymous to the ad server.
BT has revised the terms and conditions of its Total Broadband and Total Broadband Anywhere products to comply with the new rules for those who opt in the trial.
Phorm declined to say whether the ads would be paid for, how many ads would be served or who was going to advertise during the trial.
"All I can say is is that it is not the FT.com, iVillage, Universal McCann, MGM OMD or Unanimis," said a spokesman.