My husband has a Medical Alert System. He wears a bracelet with a button and when it is pressed someone calls over an intercom (the commercials "Help I've fallen and can't get up!") Well if they get no response over the intercom (which is VERY sensitive) first they call the house, then my cell, then our friends cell, then my brothers, then 911. Anyway, I told my husband if he is ever in distress and we are in the house and I cant hear him he should hit his button. If I don't hear the intercom, which they will increase the volume if noone answers(it would be hard to miss), then they will call the house phone, which I will hear or my cell which I always have. That's what we do. It's a good back up and he feels a little more secure with it.