A self configuring headset system comprising an interface unit, a method of setting up a headset system to a telephone device using and interface unit and a telephone interface unit is provided. The telephone interface unit is configured to automatically set up a headset system to a telephone device, the headset system comprising a headset and the telephone interface unit, the telephone interface unit comprising a switching unit configured to switch at least a headset transmit signal line and a headset receive signal line to a telephone transmit signal line and a telephone receive signal line, respectively, and a processor being pre-programmed with one or more telephone device permutation settings, wherein the processor is configured to receive, from the telephone device, telephone configuration information on the basis of which a specific permutation setting is selected among the one or more pre-programmed permutation settings, the processor being configured to control the switching unit according to the specific permutation setting.