Disclosed is a terminal device (10) for payment data exchange comprising interfaces for coupling to a point of sale devices (26), to a mobile phone (14), and to a payment center (1). The payment data exchange is performed on two different ways. In a first way from the payment terminal device (10) via the mobile phone (14) and the mobile voice network (5) to the authorization center (1) or, vice versa, from the payment center (1) via the mobile voice network (5) and the mobile phone (14) to the payment terminal device (10), wherein the payment data are transferred between the payment terminal device (10) and the mobile phone (14) on voice information. On the second way the data are transferred directly from the terminal device (10) via e.g. the network (5) to the authorization center (1) and, vice versa, from the payment center (1) via the network (5) to the payment terminal device (10).