O2 (UK) sale units, and with handset manufacturers, such as Apple and Samsung, to enable NFC technology on all future devices. On 23 February 2011, O2 announced it would launch a "second phase" for O2 Money, by discontinuing its branded cash cards in favour of a "mobile wallet" application for Android and iOS devices. The application would use NFC technology embedded in a phone to access money. It was announced on 9 January 2014 that the O2 wallet service would close on 31 March 2014. The BT Cellnet consumer brand was renamed O – the chemical symbol for an oxygen molecule –
O2 (UK) 2016, the European Commission officially blocked the tie-up of O2 and Three, arguing that the merger would reduce consumer choice and lead to a higher cost of services. In September 2016, Telefónica appointed a number of investment banks to sell the business to investors, ahead of a stock market flotation. On 6 December 2018, a major disruption to the O2 network, caused by faulty software, left up to 32 million users (including those on MVNOs) without access to data services (on both 3G and 4G) for up to 24 hours. During the outage, some voice and text services suffered from