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 –
The O2 sound and security technology, including RFID smart card tagging of staff and VIP guests, and digitally managed sound. There are four computer server rooms to provide this technology. The complex is also covered by CCTV and security personnel. Arena visitors and their bags are screened with X-ray machines and metal detectors at the main entrance. The O2 Arena (referred to as the North Greenwich Arena for the 2012 Summer Olympics and Paralympics) is a 20,000 capacity venue, primarily used for live music. It is located at the centre of The O2 and is the first American-style, multi-purpose arena in London.