Pressure is on US phone companies Verizon and AT&T who have been caught tracking customer’s online activity with so-called "supercookies" to increase advertising revenue. What is more shocking is that the system has been in place for two years and no one has noticed it before.

The companies create unique ID numbers that tag every piece of web traffic generated by the user. Simply, the phone carriers know what websites you're visiting even if you're surfing under the veil of a privacy mode. It means that web advertises can look at the identifiers and do a reverse look-up and figure out who you are and where you've been going across the web and build up a profile of your life.

"Verizon does offer an opt-out, but the problem is while it'll opt you out of their advertising program, it doesn't actually stop them from putting this ID onto your information. AT&T' say if you opt out, they will stop putting that ID on there, but ultimately there's no easy way to flip it off.

Apple also has similar tracking techniques for advertising, but no one talks about them because Apple owns the press. In any event, the Apple settings can be disabled in a user's privacy settings.