... System, Video Door Entry System, Video Intercom, Multi-user Intercom, Video Intercom for multi-stories Building, Video Door Phone Intercom, Digital Intercom, Intercom System, Digital Intercom System, Home Intercom System, Home Video ... .16-chord ring,30 seconds for ringing9.Function: video intercom, long-distance unlocking and surveillance.10.External dimension: 255*168*30mm(wall ...