HOLDJOY BELL is a smart home app, If you want to use it, you need an our companys smart doorbell, and add it to your apps doorbell table.
When you have set up our companys smart doorbell, No matter where you are,you can see and talk to someone when someone is ringing the doorbell.When your phone has no network,he can call you.The doorbell has alert system, if someone stands or hovers in front of the doorbell, the doorbell will record video and sent to the cloud,you can always view.