You use this for age verification? I have, in the past, visited a web site where O2 asked for age verification via a credit card payment of £1 (which was paid back immediately) So clearly this technical feature of sharing my private data didn't work in the first place?!?! Commenters above talk about an opt-out. I'd say that an opt-in for sharing private data is how this should work. That combined with the possibility for the O2 users to find out what web sites our data are shared with.