O2 is the commercial brand of Telefonica UK Limited and is a leading digital communications company with the highest customer satisfaction for any mobile provider according to Ofcom. With over 23 million customers, O2 runs 2G, 3G and 4G networks across the UK, as well as operating O2 Wifi.
If you use a lot of mobile data then we have you covered, check out the today's best Unlimted Data SIM from across all available UK Networks.