A method for operating a mobile Point-of-Sales (mPOS) application for executing a transaction includes: a Universal Integrated Circuit Card (UICC) card connected to a terminal device executes in interaction with the terminal device an application frontend of the mPOS application that provides, upon launch, an I/O interface with a human machine interface displayed by a touchscreen of the terminal device and a machine-to-machine interface; and the application frontend, for starting a transaction, captures transaction data associated with the transaction to be started via the human machine interface, reads further transaction data via the machine-to-machine interface from a transaction device separate from the terminal device and arranged close to the terminal device, generates a transaction authorization authorizing the requested transaction, and transmits the transaction authorization, the transaction data and the further transaction data via a connection to a remote backend server for completing the transaction.