To get a preview of who is knocking at your door without actually opening it, you can use a door peephole or consider a wireless video intercom that allows you to view and talk to a visitor from inside your home from an indoor monitor. This is a comfort and convenience if you're disabled or working in the house at a distance from the door.
A video monitoring system is made of two components, an outdoor speaker/camera and an indoor monitor. The indoor monitor rings and displays a picture of the visitor on the screen when the visitor presses the button on the door unit. To install a wireless video monitoring system a security company will charge $395, which includes labor and the material. If you're handy, you can buy the system and install it for $295 and save 25 percent. In addition, you'll need four connectors and wire to connect the camera and monitor together.
The bottom line: compare the price of a contractor’s bid to install a wireless video intercom with what it costs to do it yourself and make your decision. You adjust the cost to where you live by adding your ZIP Code.