O2 is the principal commercial brand of Telefónica UK Limited, part of the global telecommunications group Telefónica S.A, headquartered in Spain and operating in Europe, and North, Central and South America.

With over 34 million connections, O2 is the UK’s largest network providing 2G, 3G, 4G and 5G services and operating a nationwide O2 Wifi service.  For three consecutive years it has won Best Network Coverage provider at the publicly voted  Uswitch  Awards (2018, 2019, 2020).   It won Best Network Performance at the Mobile News Awards 2019, and was named Most Reliable Network by GWS in 2020.

The company is the network of choice for mobile virtual network operators giffgaff, Sky Mobile and Lycamobile and manages a 50:50 joint venture with Tesco for Tesco Mobile.

O2 has 6,700 employees across three main office sites and 450+ retail stores, and was named a Best Place To Work in Glassdoor’s 2019 Employee’s Choice Awards.