The device has a fall sensor which can be turned on or off using the app.
This uses a built in gravity force sensor which will trigger which subjected to a sufficient gravitational force. The sensitivity can also be adjusted within the app.
Please be aware that the fall sensor has limitations and will not always activate because not all falls will generate a sufficient gravitational force (e.g. when sliding out of a chair or falling against a wall).
In addition, the device can be set to automatically answer incoming calls from any numbers which have been entered into the phonebook - so you could call the One Button Emergency Phone with GPS Tracker and ask if everything is OK. Your call would be heard on the speaker. If you didn't get a response, this could be an indication that the person is incapacitated.