Vodafone UK customers can access their bank accounts for free from internet-enabled mobile phones.
The service, run over the Monilink mobile banking network, allows users to access banks including Alliance & Leicester, First Direct and HSBC to check their balance, request a mini-statement and top up pay-as-you-go mobiles.
Mike Eaton, head of content for Vodafone UK, told silicon.com: "Customers want to be able to access their bank accounts wherever they are and whenever they want."
The service will be free-of-charge until the end of 2007 when the banks will decide whether to start charging customers.
Eaton said each bank will decide how it will charge for the service.
Customers can register their bank or building society account for Monilink mobile banking directly from the Vodafone Mobile Internet homepage.
Once registered, the banks will send a letter to customers with login details so they can connect to their account using a secure application stored on their phone.
On accessing Monilink, the customer is prompted to enter a passcode which is registered with their bank or building society before access is granted to their account.
NatWest, the Royal Bank of Scotland and Ulster Bank in Northern Ireland are due to join the service later on this summer.
The service has been developed by Monilink as a joint venture between mobile banking company Monitise and VocaLink -- the company behind the UK's ATM network.
HSBC and its First Direct subsidiary rolled out mobile banking services to its customers last year in a deal with Monilink.