fourth controllable switches 9 13 and 29 as well as the averaging interval adjustment device 19 and the gain range preselection stage 31 are actuated via a microcontroller 33 of the mobile telephone which is connected in the normal way to its input keypad or keyboard 35 and to the display 37 and which has an associated program memory area rom 33 a and a main memory area ram 33 b this arrangement operates as follows the af level control stage 11 which fundamentally operates in the same way as automatic level control as is known per se produces depending on the specific configuration partial or complete compensation for fluctuations in the input level at the af signal input 7 a provided the first switch 9 is closed and this function is hence activated this compensates in particular for increases or reductions in the speech volume of the conversation partner in a telephone connection resulting from environmental noise if the second switch 13 is closed and the function of automatic matching of the receiver volume to the speech volume is thus activated the voltage measuring device 15 detects the speech volume level with the output signal from the voltage measuring device being subjected in the averaging stage 17 to averaging using an averaging time interval which is preselected.