The points to check before selecting a video door phone: 1. What is the distance between the interior monitor and the outside intercom? It shouldn’t be more than 100 to 150 meters away (up to 250m for VSystem Pro range) for the system to work. 2. Is there a power supply near the interior monitor? 3. Are two wires available to connect the monitor to the outside intercom? The wire gauge must be verified for the model selected and the distance. 4. Is there wiring connecting the outside intercom to the gate's motorised system and/or the electric latch release?