Telefonica UK Limited, trading as O2 UK (stylised as O2), is a British telecommunications services provider, headquartered in Reading, England which operates under the O2 brand. It is owned by VMED O2 UK Limited, a 50:50 joint venture between Telefónica and Liberty Global. O2 is the UK's largest mobile network operator, with 23.8 million subscribers as of May 2023.

BT Group plc is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, broadband and mobile services in the UK, and also provides subscription television and IT services.