Even text messaging is not immune from the recession, it emerged today, after O2, the country's biggest mobile phone operator, revealed that consumers are rationing spend on the service.

Despite the low costs of texting consumers are increasingly thinking twice before hitting the 'send' button.

The trend, revealed in the first quarter results of the group's Spanish parent company, Telefonica, contributed to a near 4 per cent drop in O2's key 'average revenue per user' (ARPU) figure in the period.

A spokesman for the group said that overall text usage had not gone down. But customers, he said, were becoming more aware of how they use their mobile phones with heavy users, for example, seeking out packages that included more texts so that were not paying for what they did not use.

The service, which was launched commercially in 1995, forms the biggest revenue generator outside voice for the phone companies. In the UK alone last year 78.9 billion text messages were sent.

Initially, texts could be sent only between users of the same network, but in 1998 the market was opened up so texts could be sent, for example, between an Orange user and one from Vodafone.

Analysts had thought mobile phone operators would be relatively unharmed by the recession. But increasingly it has emerged they are not immune from consumer cut-backs.

O2 also reported a 6.3 per cent in its voice ARPU which was in part, it said, the result of customers seeking to save money.

It had also been hit, it said, by customers travelling abroad less because of the recession and so not spending money on their phones while away.

Despite the recession, O2 added 141,753 new customers in the quarter - an increase of 2.5 times on the same time last year - to take its total mobile customer base, excluding Tesco Mobile, to 20.4 million.

Matthew Key, chairman and chief executive of Telefonica Europe, said: "In spite of a tough economic environment, we delivered a strong set of results in increasingly competitive markets."

Revenues jumped 7 per cent year on year to €1.6 billion.

The performance helped the Telefonica group to beat market expectations with a 9.8 per cent rise in net profit in the period, from January to March. It also stuck to its guidance for the full year.

Times Recommends

• Lies and cover-up at MG Rover exposed by report
• High oil prices push manufacturing costs up
• Primark founder steps down as chief executive