Aside from the basic visual intercom functions, this system enables seamless compatibility with Hikvision CCTV systems, using the door station as an outdoor IP camera for video recording via connection to a Hikvision NVR. Unit-to-Unit video calling. When applied, the unit-to-unit video calling feature can facilitate communication among owners in different apartment units. These components adopt high-performance echo-cancellation technology to ensure high quality voice transmission, providing an exceptional user experience. Built-in loudspeaker and Omni directional microphone ensures sound clarity. Convenient to install by local electrician and easy to operate. The outdoor and indoor units can be used in a 2 way communication by pressing the relevant keys. One indoor unit can be connected to 2 outdoor units. For example out door unit at the front and back of the doors can be connected to the same indoor screen unit. Similarly one outdoor unit can be connected to 3 indoor units. For example outdoor unit at door can be connected to indoor units in Kitchen and bedrooms.