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) of MVNO networks Tesco Mobile and Giffgaff. To apologise for this, O2 announced that it would be giving hundreds of thousands of its customers compensation for the issue. Pay monthly customers received a 10 per cent discount on their bill whereas Pay As You Go users received a 10 per cent refund on their first top up in September. On 24 November 2014, it was reported that BT were in talks to buy back O2, while at the same time BT confirmed that it was also in talks to buy EE. BT subsequently entered into exclusive talks with EE. On