The fall sensor watch will detect heavy falls (i.e. a fall which renders the person unconscious). Common with other fall sensor watches, it won't detect low impact falls - for example, a person sliding down the wall.
There is a built-in call button that the person should always press if they fall and are able.
If the person has a memory problem (e.g. dementia) and might not remember to press the button, consider a 'not returned to bed sensor' which will alert you automatically if a person does not return to bed within 20 minutes.
View Fall Sensor Watch Instructions & Specification