After a flurry of complaints, O2 engineers appear to have shut off the proxy server quirk that leaked to websites the phone numbers of punters browsing the net on 3G connections.
The disclosure that affected all users of O2's 3G network on iPhone and Android in the UK was highlighted earlier today. O2 has yet to issue an official statement on the matter, but we can imagine wonks working furiously in the background to fix the blunder. The telco described its investigation of the issue as a priority.
Quick tests show that the HTTP header including the telephone number is no longer present in requests sent to website servers via O2 UK's network. The telco's proxy systems strip out that info, or simply don't append it in the first place, before it's sent out to the world wide web.
We await O2's statement on the reasons for the number-leaking blooper. ®