Payment transaction method and payment transaction system in which payment transactions between customers with portable mobile devices, for example mobile radio telephones, and a plurality of payment terminals are carried out at a service point, the payment terminal responsible for a payment transaction informing a respective customer about the total transaction amount and the transaction identification of the payment transaction, the transaction identification comprising a payment terminal identification, the mobile device transmitting, via a contactless device interface, the transaction identification, entered in the mobile device by the customer, to the payment terminal, identified through the payment terminal identification, the payment terminal transmitting, after receipt of the transaction identification, a payment request comprising a service point identification, the payment terminal identification and the total transaction amount, via the contactless device interface to the mobile device, and a payment record which comprises the payment request and a customer identification, being prepared in the mobile device and being transmitted from the mobile device via the contactless device interface to the payment terminal.