Abstract: The radio unit of a modern radio telephone comprises a plurality of controlled two-position switches. Each controlled switch most often requires an individual control line from a processor. The greater the number of controlled switches in the circuit, the more control lines that are needed. The number of control lines is substantially reduced in that from one or several control lines of a frequency synthesizer in the radio unit, a switch line is branched off for the controlled switches. During the time in which the synthesizer circuit receives no control signals, the logic unit of the radio telephone supplies a control voltage to the controlled switches over a control line of the synthesizer and over a switch line branched therefrom.