O2 (UK) cent share of Cellnet for £3.15 billion. Cellnet had five million customers at the time of its acquisition. The company was later rebranded as BT Cellnet , and it became a part of BT Wireless, a group of companies owned by BT. BT announced on 3 September 2001 that the BT Wireless business would be spun off from the main group as a newly listed holding company, mmO2 plc, operating under the "O2" brand. Shareholders approved the plan at an extraordinary general meeting on 23 October 2001. BT Cellnet relaunched as "O2" on 18 June 2002, along with other former
O2 (UK) manufacturing Near Field Communication (NFC) technology in mobile phones in the United Kingdom. O2 and Vodafone signed a deal in June 2012 which will see the two companies 'pool' their network technology, creating a single national grid of 18,500 transmitter sites. Both networks will continue to carry their own independent mobile spectrum. In July 2012, O2 had to apologise to almost 8 million customers after a network switching subsystem failure led to a 24-hour blackout of the service across the UK and Ireland. The problem, which prevented a third of its customers' phones registering on the network, also affected customers