How it works
Geofencing uses a virtual boundary around a place to infer arrival or departure from a phone’s reported location. The automation platform compares location updates with that boundary and may trigger actions when the state changes. It describes the phone’s estimated position, not a direct observation of a person entering a building.
Important differences and limits
Accuracy and timing depend on location permissions, mobile operating system restrictions, signal conditions and update delivery. A phone left at home can report presence while its owner is away. An overly small boundary may produce repeated changes near the edge; a large one may activate routines earlier than intended.
A useful practical check
Review background location permissions and battery restrictions on the actual phone. Test ordinary journeys in both directions and compare event times with real arrival. Decide how multiple residents should affect the rule. Keep a manual alternative and avoid treating location alone as dependable evidence for critical access or safety decisions.
An example in practice
For example, arrival could enable a welcome lighting routine only after dark. If a road passes close to the house, driving nearby may also cross the boundary. Add appropriate conditions, test that route and inspect the history before expecting consistent behaviour. A useful comfort feature should still make sense when an update is delayed or absent.