Abstract: A PC containing a softphone is connected to a headset (14) by means of a control unit (9) which is connected to a USB gate (6) in the PC. The PC has a security function, which means that the PC can be accessed only by users who e.g. know an access code. The control unit (9), comprising inter alia a sound card, is equipped such that also commands may be given to the softphone (15), even if for security reasons the PC is blocked e.g. by a security code, it being possible to transfer a limited number of commands via the USB gate (6) from the control unit (9). The invention ensures that, irrespective of the state of the PC, the softphone can always be used, as the control unit (9) always gives access to it, which may be important, e.g. in connection with an emergency call.