Petfon tracks our dogs based on GPS and LoPoWan technology. It transmits signal via Bluetooth and LoPoWan, not mobile signal, cellular network or wifi signal. That means you don't need to use any internet during the usage of our devices. It enables you to track our dogs in some very desert areas with no cellular signal. Even if there is no cellular or wifi, our devices would run normally as long as your cellphone's Bluetooth is enabled.