Detecting when an elderly person falls

JLDohm writes: My grandmother isn't getting any younger, and the risk of a fall seems to be increasing daily. Google helped me find a lot of products that will place a phone call if she presses a button, but what if she is unconscious? I found one company that seems to offer a product that automatically detects falls, and calls regardless of whether a button is pressed or not. It seems to me like this would be a fairly complicated thing do to. Does anyone have experience with this product or any other product that does the same thing?