mmO2 is a British telecommunications company specialising in mobile phones.
Previously named BT Cellnet and Cellnet, mmO2 was created when British Telecom, the main fixed line provider in the United Kingdom divested its mobile phone business, BT Cellnet by a stock market floatation. The BT Cellnet consumer brand was renamed O2, the symbol for oxygen. mmO2 owns mobile phone businesses in the UK, Republic of Ireland and Germany.
In the Republic of Ireland the O2 Ireland network is the former Esat Digifone 086 GSM 900 network which was set up in 1997. It currently has a 40% market share, 1.27 million customers.
mmO2 is the seventh largest mobile phone operator in Europe with 20 million subscibers. Its stock market value is approximately £10 billion making it a FTSE 100 Index company.
In February 2004, the company was subject to rumours of take-over bids from KPN, the Dutch telecommunications group.