A mobile telephone is easy to carry around but has a small keypad and a small display. A normal deskphone has a big keypad and display and has a convenient handset, but is stationary. A stationary communications terminal is described which is connected to a mobile telephony network via a mobile telephone. The mobile and the stationary terminal have each a BLUETOOTH radio transceiver and are interconnected via a BLUETOOTH link. The stationary communications terminal lacks identity in the mobile network. A subscriber, owning the mobile, can call on the stationary communications terminal and can move to another network having another stationary terminal, on which he can make a call. Another subscriber with a mobile can call on the communications stationary terminal. To prevent misuse the subscribers take an authentication code for his respective mobile on the stationary terminal, and the authentication can be made valid for a predetermined period by taking a service code.