Many of today's Smart Doorbells are equipped with motion detectors.
There are two primary reasons why it is advantageous for you to have a video camera doorbell or Wi-Fi doorbell with Motion Sensor; 1) it will help to eliminate surprises when someone has approached your entryway but has not pushed the doorbell button, 2) if you are not around when someone has knocked on the door and is waiting for you to respond you will still be able to see and talk to your visitor.
Unlike other entryway motion sensors that are set for very broad scanning and instant response, your video doorbell or wifi doorbell sensor may be set for a very narrow field to prevent false alerts. The sensor could detect motion up to 5-feet away, and will then wait up to 10-seconds before it sends an alert to your smartphone. This allows for positive detection that someone is waiting at the door. This also prevents false alerts when someone, or something, goes past the door but has not stopped, i.e. someone passing by, a wandering dog, a passing bird in flight, or more often a family member who is using a key to come into the house through the front door.
Locating your video camera doorbell or Wi-Fi doorbell with motion detector as close to the door as possible provides the best performance for detecting motion. However, if your doorbell placement is located away from the door, you may use an accessory to assist in getting better positioning so smart home doorbell is angled towards the area in front of the door. This will help you see better when using the video view as well as improve motion sensor performance.
Yes, the video camera doorbell or Wi-Fi doorbell with motion sensor mobile app may allow you to turn on, and turn off the sensor feature at any time. For those times when it may be more convenient to have the sensor off because you have foot traffic through the front entry, you can switch the sensor off with a single button in the app.