How about home alarm systems? Home alarms used to just be a buzzer you attached to your door that had a switch to turn it off. Along came the company that add

How about home alarm systems? Home alarms used to just be a buzzer you attached to your door that had a switch to turn it off. Along came the company that added a pin code and connected the system to a phone line to monitor it for you. If the alarm tripped they could call the police on your behalf. Sure, the phone line could get cut, but you're still no worse off than you were before.