RF Telephone Transmitter Acoustic (Lisa RF)

Do you have an external telephone connection without a removable plug, such as a wall telephone in the hall? Or perhaps a digital company telephone exchange or ISDN lines?
Then with the LISA RF telephone transmitter AC you can still hear the ringing telephone and see it with a flash lamp in the room where you place the receiver. You simply stick the microphone near the bell on the telephone.
This so-called acoustic telephone transmitter is able to filter out annoying ambient noise almost completely. The transmitter is equipped with a person call button and a selector switch for 10 channels. You will receive this telephone transmitter including an adhesive microphone and a 9-volt block battery.