The tracker works with a GPS chip installed in the device. To send the data across to the app, a low cost SIM subscription is required to cover the costs of this service. In both cases, our subscriptions are network agnostic. This means they are not tied to one specific network (e.g. O2, EE) but use all of them (whichever is strongest). This minimises network shadow areas and maximises your tracking. European wide coverage.