A headset base unit comprising a base housing, a first connection device, by means of which the headset base unit is connectable to at least one telecommunication device, such as a desk phone or a PC phone. Furthermore, the headset base unit comprises a second connection device, by means of which the headset base unit is connectable to a headset, and a device holder for holding a mobile communication device with a device user interface. The headset base comprises control means, by means of which an audio channel can be opened between the headset base unit and a selected one of the telecommunication devices. The headset base unit is adapted to receive control commands from the mobile communication device for controlling the selected telecommunication device connected to the first connection device, whereby a user can control the telecommunication device by means of the device user interface.