It is an interesting question, though it doesn't apply to me. But it had me looking for historical reference to an emergency number. I had one of those 'positive' memories of us having 999 and then changing to 000. Wrong, my memory of 999 had to relate back to England where I was born (the single number for emergencies had been in use there since long before I was born). The time I thought was a 'change' was actually the implementation! Still, I can say htat Australia has a single nation-wide emergency call number, for Police Fire and Ambulance.
Unfortunatly I live in an area with no 3 digit emergency number. At the present time we dial 7 digits and soon I can see 10 on the horizon. No I do live in a remote part of Missouri, but given the fact that a 4 lane highway run through the area and only being a hour south of Kansas City I don't understand why it is available in my county.
Since we are in a new era of communications why isn't this mandated at a state or federal level?