If you don't have WiFi in your home, or if your WiFi connection goes down, the Owlet Baby Monitor is designed to still function.
The Base Station communicates with the Smart Sock via Bluetooth, so in the event of any notification, the Base Station will notify you with colored lights and audible sounds. It will also let you know that your child's readings are normal with just a glance - showing pulsing green when readings are normal - so that you don't have to obsess over the data.