Ok. It cannot detect ring in my case with this setup. Equipment is slightly different, so I will explore further. As analog I am not seeing how it would detect the ring, since it is codified (not analog) thus asking, maybe you are not using a 2 wire system (same wires to all apartments, using codes to identify ringing, and your wires come directly from the intercom downstairs. I have 10 apartments, which is usually already above direct connection systems. But happy to be able to open the door at least!! Main usage for me.