emergency fall alarms

there were questions asked sometime ago about emergency alarms I have just spoken to my technical adviser [son] about apps for smartphones and if the movement sensors would be sensitive enough he said they should be so I looked and this came up

CRADAR: Android Motion Sensing Application That Sends Out An Alert If You Fall it appears to be a free app the site I found it on is makeuseof.com/dir/cradar-mo... I don't know how good it is and I don't have a smartphone to try it just my dorio bulletproof brick so it would be nice to know if someone tries it and tells everyone