BT is pressing ahead with its trial of Phorm, the controversial behaviour-based advertisement serving technology, despite mobile network operator Orange saying it is dropping plans to use Phorm.
This follows two secret tests last year of the Phorm technology on unwitting BT internet customers.
A BT spokesman said the trial started on 30 September. He said BT aimed to recruit 10,000 users by invitation to BT Retail customers, not from the public.
The BT spokesman said BT had decided not to disclose how many people it had asked to take part so far, nor how many had joined the trial. He expected the results to be made available once it had been assessed. He declined to give a publication date.
Ofcom, the communications regulator, has said it is crucial that customers "opt-in" to schemes that collect information about their online activities to build up profiles of their interests and social networks. In a letter to the European communications commissioner's department, it set out compliance guidelines for Phorm, and any ISP that used Phorm to target adverts at customers.
Phorm has been at pains to explain itself. It defended itself at an unprecedented public "town hall meeting" in London, and recruited civil liberties watchdog Privacy International to audit its software and processes.
No other system that delivers advertising based on behaviour profiles, notably Google's AdWords service, has faced similar scrutiny.
The US Federal Trade Commission held hearings a year ago into behaviour profiling systems for marketing purposes. It then issued guidelines advising operators to warn people when their web activities were being recorded, and give them a chance to "opt-in".