o2 security allert incase you dont know,

[Google]

Incase you dont know its on sky news, o2 have a security alert, that evey site you visit on your phone will give them your number displayed, which has lead to a high volume of unwated sales and flyers to your phone.

but may have been fixed now.

also to add....... theres a sim card called giffgaff they run of 02 network aswell.

[MelC]

This link explains the o2 security alert

Sophos