Have installed the system on the old bell. When you press the door intercom, now ringing the normal doorbell and the phone. Very convenient. The phone does the job. Is with us now in the bedroom. If everything is connected to a Fritz box. Commissioning was a fumble. Fortunately there gift already detailed recessions where everything was well described. I can recommend the Indexa.
Update 15/12/2013 Have downloaded from 5 to 3 stars. The door intercom system does not work properly. The phones do not ring anymore. Already changed batteries once, then we went back few days ..... Would I then no longer buy or not for the price.