False calls with Bitron AN0002, looking for suggestions

I correctly linked my Ring Intercom to a Bitron AN0002 (5 wires) analog intercom. Everything works fine, speaker volume is pretty good. The problem is with false calls: every time someone is ringing to ANOTHER apartment, some induced current on "CALL" wire is activating ring-intercom.Do you have any ideas on how to solve this problem? What about using a relais to separate CALL line from the intercom to the CALL line wire of RING Intercom?