The FitBark GPS uses an embedded sim card that taps into 4G LTE-M cellular networks to communicate with our servers and the FitBark app. In the same fashion as your mobile phone generates data fees, the SIM card integrated in the FitBark GPS generates data fees. Your subscription helps us cover these costs, as well as other third-party charges we sustain when we need to get an approximate location of your dog by scanning Wi-Fi networks nearby.