The mobile operator's UK division saw a 10.6 per cent rise in annual sales, while Spanish parent company Telefónica posted a 5.9 per cent annual rise to £12.7bn.
O2 claimed that it added 499,000 fixed and mobile customers in the UK in the last quarter of 2008, bringing its customer base to almost 22 million. Even as the credit crunch got underway, O2 managed to keep its sales up by 10.4 per cent over the previous year's quarter.
Telefónica also reported a rise in yearly sales of 2.7 per cent to £51.76bn, fuelled mainly by a growing Latin American market.
Matthew Key, chairman and chief executive of Telefónica Europe, said in a statement that the firm's good financial performance was down to "customer satisfaction and the success of our products at the top end of the market, including BlackBerry and iPhone".
Key called on the government to work with regulators and the industry as a whole to ensure that regulatory clarity would favour investments in R&D and new infrastructure.
"The mobile phone is part of people's everyday behaviour," he added, eager to show that the economic crisis would not cause people to give up their phones. However, Key did note that Telefónica is still concerned about the state of the markets.
Competing operator T-Mobile demonstrated that Key's concern is not entirely amiss, having lost 16,000 customers in the fourth quarter.
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