I got false geofence alert emails/SMS.

Due to the fluctuation of the GPS signal, you should not set your fence radius too small. We recommend setting greater than 500 feet. Less than that will trigger lots of false alarms.

With 500 feet fence, you could still get 1 or 2 false alarms if there are any factors that cause more GPS drifting in your area (high buildings, thick clouds, storms...). In such cases, you should increase the fence radius.