Abstract: A method and system for operating a banking service are included. The system includes a database (12) for storing client registration data and a unique number, which is preferably the MSISDN or mobile telephone number of the client. This number is used as the client's account number. A call center (14) receives calls from clients and verifies their identity from data transmitted by their mobile telephones. The system allows clients to conduct various banking transactions including balance, statement and payment transactions. A database stores details of balances and/or transactions in each user's account. The system serves for clients to be notified by an SMS transmitted to their mobile telephone of transactions, such as changes to their bank balances or the crediting or debiting of their account. The system can also interface with conventional banking services.