O2 (UK) Telefónica O2 had a long-standing relationship with Arsenal F.C., being their shirt sponsor until the end of the 2005/2006 season. In 2005, a three-year deal was signed that saw Telefónica O2 become the team's exclusive mobile communications partner. O2 were the main sponsor of the Channel 4 reality TV show "Big Brother" from its second series (as BT Cellnet) in 2001 until its fourth series in 2003. They also sponsored the spin-off shows "Celebrity Big Brother 2" in 2002 and "" in 2003. In total O2 sponsored five series of the show. O2 sponsored music festivals, the Wireless Festivals, from
O2 (UK) 23 January 2015, Li Ka-shing, owner of Hutchison Whampoa and the Three network (which operates in the UK) entered talks to buy O2 for up to £10.25bn ($15.4bn). However, the move faced tough scrutiny from competition regulators as it would reduce the number of major operators in the UK, when combined with a potential purchase of EE by BT, from four to three. Hutchison Whampoa had previously acquired the O2 network from Telefónica in the Republic of Ireland, which it has since merged into Three. The combined network would have surpassed EE to create the largest mobile network in the