Vodafone announced yesterday that the number of people with mobile phones has been overestimated by as much as 10 percent. This still means around six out of 10 people have a mobile phone.

The mobile phone telco admitted its own figures, recorded in January, were overestimated by 9 percent. The figures erroneously included people on prepay services who no longer used their phone or who had upgraded but held on to their old handset.

"We need to alter the way we calculate figures… due to the number of people using pay-as-you-go services," said a Vodafone spokesperson.

Vodafone believes mobile operators have counted a proportion of their customer base that are 'inactive'.

Orange agrees. "A universal method of recording figures needs to be established," said an Orange spokesperson. "We need to work out the value of the customers, rather than just the number of customers."

Orange refused to confirm whether its figures were also overstated.