Geo-fencing is a tactic made possible by the emergence of smart phones and mobile devices, uses the applications of GPS (Global Positioning System) or RFID (Radio Frequency Identification). These certainly works with Satellites.
In Accurate definition:
Geo-fencing, or geofencing, is a term that refers to software tools or applications that utilize GPS or RFID to establish a virtual perimeter or barrier around a physical geographical area.
Internet of Things, which deals with API (Application Programming Interface) has used GeoFencing, can be enhanced in few of the applications such as,
Philips Hue Connected Bulbs
> Philips used GeoFencing, so that you can control your light bulb with your smartphone.