I have this 99 cent switch installed in my door phone, because you can not turn off the ringer. What do not get well-paid developers these intercoms, install a stupid off switch for the ringer, you can easily and cheaply retrofitted. Finally, I can sleep again after the night shift, without being awakened by the deafening sound of the bell, if the mailman all ringing in the house simultaneously presses. And for lion euros!