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 the total transaction amount, via a communication network (3) to the central transaction unit (4), and the central transaction unit (4) transmitting a payment request, comprising at least the total transaction amount, to the mobile device (1) from which the transaction initiation record was transmitted.