A method is provided for operating a directory assistance system is provided that includes the arrangement for storing a plurality of directory listings including listings relating to identification of Voice over IP devices. Inputs from a multi-dwell table and a finger control table are multiplexed by a first multiplexer. The driver element includes a first driver element and a second driver element which are provided on the mounting surface at different positions in a longitudinal direction of the actuator body. A second oscillator circuit operates with the second resonator and outputs a second oscillator output signal having a second oscillating frequency. The spark-gap is characterised in that the negative discharge electrode includes a corona effect device equipped with needles whereof the geometry is adapted to compensate for the differences in shape between the negative discharge electrode and the immediately adjacent intermediate electrode so as to ensure a homogeneous distribution of the potentials inside the sealed chamber.