Lewis Peckover, who set up a little web tool that displays all the “HTTP header information” sent to sites by web browsers, highlighted yesterday that O2 include your mobile phone number whenever you visit a website whilst running over the 3G network.
Users of the social news site, Reddit.com, confirm this problem also happens with Tesco Mobile.
For O2 and Tesco customers browsing on a 3G connection, these headers also include their personal telephone number in an
x-up-calling-line-id line. Enterprising website owners can easily keep a copy of the HTTP header information sent over by visiting browsers and tie it to IP addresses and logins, if applicable.
O2 commented on their Twitter feed:
@lewispeckover Hi Lewis. The mobile number in the HTML is linked to how the site determines that your browsing from a mobile device #O2Guru (https://twitter.com/#!/O2/status/161872584634408960)