Possible ? Detecteing if a device has passed through a geofence

Hi,

I am wondering if it is possible to detect our get an event when a device has passed through a geofence ?
Lets say I have a geofence at a set location with a certain radius. I have two points one before the geofence and one directly after. Is it possible to get an event for this or maybe a calculation ?

Thank you for a fantastic piece of software guys !

Regards
Tommy

If device doesn't actually get inside a geofence (reports location from there), you won't get an event.

so when it hits the line/fence either going in or going out all alerts are possible?