The handsetfrom the intercomhas an establishedreason,sothatitcan be usedas a replacement for oldmodelswithoutfearofvisibletraces of theirinstallation.Thisbutton is illuminated by an LEDindicating a call. The nextbuttonallows you to control an externalsource, for example, the drive of the entrancegateor the lighting of the stairwell. It is possible to install a push-buttonmoduletocontrolanotherexternaldevice.