My MIL recently fell and broke her hip. She fell in her back yard around dusk, but managed to crawl or drag herself to the front drive where a neighbors teenagers just happened to see her. After replacement she wanted to return home ( stubborn 85 year old) where she lives alone. We had the concerns you have stated, along with the knowledge that her fall situation could have been disastrous had no one seen her.
We did a little research and settled on the system by American Senior Safety agency. She has had it now for about 6 months with no problems. Her wrist worn activator was accidentally pushed about a month ago , and the company was on the phone immediately. They also WANT her to test the system at least monthly, and are very courteous as she goes from room to room checking to see if her voice can be heard. THey also have the lock box feature, which would save a broken down front door. ( that happened to my father in his later years, no lock box, firemen/ems broke door down getting in).
In short, those monitored systems are worth every penny both in actual safety and peace of mind to those who cannot be there at all times to watch the elderly. You wont regret making that move.
Thanks William. I did go with the Lifestation, and just got back from installing/testing the unit. I would have had this done yesterday, but forgot she would need a DSL filter.
The system does seem to work well. I feel better with her having it, and she feels better, too.