O2 Accused Of Sharing Customers Phone Numbers Every Time They Visit A Website

UK network O2 has been accused of giving away customers phone numbers every time they visit a website using their mobile device.

The Verge reports that the numbers are included in the information sent to websites on connection.

British cellphone carrier O2 appears to be sending customers' cellphone numbers in HTTP header traffic, inserting the info in data sent to websites over O2's connection. Lewis Peckover discovered the problem this week and setup a website to document it. The site allows O2 users in the UK to check to see whether their number is being sent along with HTTP traffic. We have confirmed the issue on two O2 numbers in the UK, and our testing with other networks indicates it is isolated to O2. Orange, Three and Vodafone were unaffected in our tests.

O2 says it is "investigating this at the moment and will update everyone as soon as [it] can," but customers have reacted in anger on Twitter this morning. The issue appears to stem from O2's use of transparent proxies, common for cellphone network providers. The proxies allow firms to balance network load, but carriers typically inject a unique identifier into HTTP headers to help webmasters identify visitors with non-personal information. We're waiting to hear more from O2 on the matter, and we'll update you accordingly.

It appears it's also happening with the smaller carriers that use O2 as their network, like Tesco Mobile and GiffGaff.