To provide fixed volume from a speaker regardlessly of position of microphone.

This system is provided with a 1st load resistor R12 connected to a calling button 1b, 2nd load resistor R13 for increasing the level of transmission while being connected to a calling grip button 5, 1st transistors Tr11 and Tr51 which are respectively turned on when that button is depressed, and respectively connected to the 1st load resistor R12 and 2nd load resistor R13, and 2nd transistors Tr12 and Tr52 which are turned on by turning on the 1st transistors Tr11 and Tr51 and form a holding circuit together with the 1st transistors Tr11 and Tr51 when the depression of that button is canceled. Therefore, when using the calling grip button, the 2nd load resistor R13 is functioned for increasing the level of transmission from a microphone 1m of handy type hand set 1 but when performing calling from the calling button, the 1st load resistor R12 is functioned and on the speaker side of base unit 2, suitable volume can be provided at all times.