Growing the number of financial transactions across mobile networks will depend on payment transaction costs, revenue share issues and overcoming customer support difficulties.

800 million people will bank via mobile devices by 2011, according to a report from Juniper Research.

Meanwhile US online banking numbers declined for the first time in five years. Although 47 million Americans said they used online banking, the rate of growth slowed in the fourth quarter of 2007 and last year saw the first decline in online banking.

"After several years of strong growth in the number of users of online banking services, it appears the market is entering its next phase," says Brian Jurutka, of research house comScore. "Many of the top banks are realising that customer servicing is of increasing importance… and are investing resources in online and mobile banking."