TalkTalk broadband had pulled the plug on its agreement with Phorm, days after BT made a similar move.
BT, a key player in the development of Phorm's Webwise system, announced earlier this week it would dump the company.
Phorm has developed technology which collects information on individual's web habits in order to serve targeted adverts. But the system has proved extremely controversial.
Despite claims by Phorm that it 'anonymises' the information about web users so they are impossible to identify, the service has attracted a number of concerns from privacy campaigners, in particular, the Open Rights Group, which contacted big tech companies including Amazon and Microsoft asking them to ban the service.
The ORG said it felt Webwise illegally intercepts web users' communications and could commit long-term damage to the brands that adopt it.
Following the ORG's plea, both Amazon and Wikipedia announced they would stop Phorm from tracking users' activities on its web pages.
Phorm is also being investigated by the All Party Parliamentary Communications Group (apComms), as part a larger inquiry into internet traffic and the role of the government in regulating ISPs.
Unlike BT, which has actually trialled the service, TalkTalk, a Carphone Warehouse subsidiary and the second biggest broadband provider in the UK behind BT, had only had an agreement with Phorm and had not implemented any trials. Virgin Media also has an agreement with Phorm.
"We are investigating the use of Phorm's technology under our existing agreement with the company but, due to the complexities of the proposition, we do not have any timescales on when, or if, we will progress to trial or launch," said a spokesman for the ISP.
Phorm announced that TalkTalk Telecom had not trialled the service. "The directors note that this relationship had not extended to any form of trial in contrast to BT and some international internet service providers," a statement from Phorm read.
It is believed that privacy was not a factor in BT's decision to pull the plug on the technology.
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