The invention relates to the carrying out of verification processes with regard to authorization of user and/or payment processes by means of a mobile telephone terminal, whereby an identifier associated with an authorized user and/or payer is provided in such a way that it can be called up and represented on a display device of a mobile telephone terminal associated with the authorized user and/or payer. On the instructions of the authorized user and/or payer, the identifier is represented on the display device and optically scanned in an interrogation station. A control message with a request for confirmation of a process verifying the authorization of use and/or payment process is transmitted to the mobile telephone terminal. In order to grant use and/or carry out payment, the control message receives a reply by transmitting a confirmation message from the mobile telephone terminal to the interrogation station.