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 Czech Republic O2 Czech Republic O2 Czech Republic (operating under the O brand) is a major integrated operator in the Czech Republic. It is now operating more than six million lines, both fixed and mobile, making it one of the Czech Republic’s leading providers of fully converged services. O2 Czech Republic operates a fixed and mobile network including a 3rd generation network, CDMA (for data), UMTS and EDGE, enabling voice, data and video transmission. O2 Czech Republic is also a provider of ICT services Previously two companies, fixed-line operator Český Telecom and mobile operator Eurotel, it was acquired by the Spanish company