To provide arrangement for providing e.g. credit to a customer via cellular system telephone set with an authorized transaction controller.

The arrangement is provided e.g. by starting up the cellular system telephone set 10 by the customer requesting the credit in purchasing commodities or services from traders, authorizing the cellular system telephone set 10 to the base stations 20, 50 of the service provider of the cellular system telephone, and setting up coupling so as to obtain the credit. The customer obtains the credit by transmitting the peculiar sequence different from the ordinary number sequence corresponding to a callee telephone number. The identification code of the trader and the desired amount of credit are included in the sequence.