A communications unit, preferably a headset, has a number of control knobs (2, 3) for adjusting the electrical properties of the headset and is suspended by an ear hook, which may be adjusted such that the headset may be used on both the left and the right ear, said headset when switching from one ear to the other being rotated 180°, while the position of the ear hook is unchanged. In order to ensure that the functions of the control knobs (2, 3) relative to their positions on the headset are the same, no matter whether the headset is carried on the left or the right ear, a gravitation switch is arranged in a printed circuit board which is mounted in the headset. The gravitation switch of the headset provides for automatic switching of the functions of the control knobs without intervention by the user, when the headset is switched from a position on one ear to the other ear.