I think the problem with calling 911 is that it is free when it should cost enough money to weed out the noise.
If a call to 911 cost $100, how many people would be calling in about their tooth-aches/loneliness (http://money.cnn.com/2009/08/24/news/economy/healthcare_911_...)? Increase the dollar amount until the number = 0.
An app that allowed you to purchase credit before you had a crisis (or came with $100 of credit and you had to top off after an emergency) might help reduce that noise.
What if the $ went directly to the first responder?
There are ways to solve these problems.
Also, when you drive that "false positives" number to zero you also introduce false negatives. People will wait until it is too late to call 911. This could actually have all kinds of negative externalities, like the police getting into more shootouts because things were allowed to spiral out of control.
This is all beside the fact that you are assuming that everyone who would ever need to call 911 has $100 lying around to "top-off" an app (how do people without smartphones use 911, by the way?).
I'm saying there is a number between $0 and $1,000,000 per call that will help reduce false positives and make the system more efficient. Maybe its $100, maybe its $50, maybes it $5, maybe its $0.
I've always appreciated what London did to solve its traffic congestion problems (http://grist.org/news/the-success-of-londons-congestion-char...) and while I understand they are not truly analogous, I'm a believer in using $ to properly align incentives and make a system more efficient.
So while crews are off dealing with those non-emergencies, they are unavailable to respond to things like cardiac arrests and strokes...
Your husband is beating you, but you don't have your own income? Sorry, out of luck. You're poor and unemployed and having a health emergency that will probably already bankrupt you? Lets throw an extra charge on top of there just for you.
>What if the $ went directly to the first responder?
I'm assuming you mean for these people to respond when they're off duty. It varies from state to state, but generally speaking I'm covered by Good Samaritan laws as long as I'm doing what I'm doing without expectation of compensation (if I'm on duty, I'm covered by my employer's insurance). So as soon as you offer to pay me, I'm no longer covered, and I'm not going to touch you with a ten foot pole.
"...tragic consequences last year when Sally Geeson, a student, was abducted and murdered in Cambridge. Sally, whose phone had run out of call credit, sent a series of texts asking for help to friends, apparently not realising that she could have made a 999 call for free."
I really believe that this would be a more efficient system on the whole.