Abstract: A payment transaction method between a customer with a portable mobile device and a service point includes determining, at a payment terminal of the service point, a total transaction amount to be paid and a transaction identification that is different from other transaction identifications used for other transactions and assigned to the total transaction amount. The method includes informing the customer about the total transaction amount and the transaction identification. The method includes transmitting, from the payment terminal, the total transaction amount and the transaction identification to a central transaction unit. The method includes transmitting, from the mobile device, the transaction identification without inclusion of the transaction amount to the central transaction unit. The method further includes transmitting from the central transaction unit a payment request including at least the total transaction amount to the mobile device.

Abstract: Payment transaction method and payment transaction system in which payment transactions between customers with portable mobile devices (1), for example mobile radio telephones, and a plurality of payment terminals (2) are carried out at a service point (5), the payment terminal (2) responsible for a payment transaction informing the respective customer about its payment terminal identification and a total transaction amount, the customer indicating the payment terminal identification to the mobile device (1) and the mobile device (1) transmitting a transaction initiation record, comprising the payment terminal identification as well as a customer identification, via a contactless device interface (11-21) to the payment terminal (2) as well as via a mobile radio network (6) to a central transaction unit (4), the payment terminal (2) transmitting, after receipt of the transaction initiation record, a transaction placing record comprising a service point identification, the payment terminal identification and th