You're happily browsing your favourite sites using O2′s network

If you're browsing the web on your phone or tablet on O2 UK, then the network could be exposing your phone number to every website you visit. O2 customer Lewis Peckover recently discovered that when you're browsing over 3G on O2, your handset's phone number is often included in the HTTP headers sent to each website you visit, in plain text.
HTTP headers are information exchanged between your browser and the web server before a page is loaded. In theory, the way O2 includes your phone number -- alongside more mundane information like your IP address, browser and OS -- means that any website you visit could easily find out your number. It's worth pointing out that the header used by O2 to send phone numbers -- "x-up-calling-line-id" -- isn't one that's routinely logged by web servers. However, just a couple of lines of code would allow a malicious server to find your phone number just by having.......
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