Here is another smart doorbell that lets you see who is knocking on your door. The Momentum Knok Doorbell has a 1080p resolution camera and infrared LEDs for night vision. It has a 130-degree view angle and lets you see a live feed from the camera on your smartphone.
Knok facilitates 2-way communication. It is smart enough to detect motion and send instant mobile alerts. Users can customize the rules and motion detection zones and activate the 110db security siren through the app.[where to get it]