Add an additional IST V500 Smartphone Video Doorbell to your IST Video Doorbell Entry System, and let visitors ring your doorbell from a second location, such as a back door or a gated driveway. This video doorbell station works just like your original video door unit. When the camera detects motion or a visitor presses the call button on the video doorbell, you'll receive an alert on the indoor monitor and your smartphone. You'll then be able to see who is at your front door and communicate with visitors without having to open your door.