O2 (Telefónica UK)
TelecommunicationsEngland, United Kingdom5001-10000 Employees
O2 is the commercial brand of Telefónica UK Limited and provides mobile and digital communications services in the United Kingdom. It serves more than 23 million customers and operates 2G, 3G, 4G and 5G networks nationwide, and it runs O2 Wifi as well as owning half of Tesco Mobile. It operates more than 450 retail stores nationwide. It sponsors The O2, O2 Academy venues and the England rugby team. The company is based in Reading, England, and operates within the UK telecommunications sector with a broad nationwide network. In June 2026, Telefonica UK Limited announced a partnership with Cellnex Group to address 5G coverage gaps along the Brighton Main Line.