Attention, you must pay close attention to compatibility. The part is only built for simple, especially old bell setups without a bus system. As soon as you have an intercom system, for example, it won't work. I guess most houses in Switzerland can't use it, or only with additional effort. With an additional power supply unit and a relay, it can also be installed in modern flats, but then you have to have some knowledge of the subject. It rings as before + on all mobile phones on which you have installed the Netatmo app. I think it's pretty good.

All bells that are previously connected to the doorbell will continue to ring. What is certainly not possible is for a video doorbell to be heard by all tenants in an apartment building. The video doorbell will be replaced by a "normal" button. This means that a video doorbell would have to be installed for each tenant.