To function, this doorbell system requires both the doorbell unit and the accompanying hub (H200) as a kit; the hub must be set up first before the doorbell. A smartphone alone is not enough, as the hub connects the doorbell to your network and app. You do not need to purchase a subscription to use the system's features. The setup involves configuring the hub via the Tapo app, then connecting the doorbell to the hub, with both devices on the same 2.4GHz Wi-Fi network. The doorbell is powered by a rechargeable battery and controlled through the app on your smartphone without additional stations or subscriptions.