Iphone coverage - sos mode

I live in an area with limited coverage. Often i get "SOS" in the signal strength spot. If this happens, i presume i can make an emergency call but if there's no coverage i don't know how it works. do i still dial 000 as normal and get through to emergency services or is there some other way to access SOS in emergency situations? I don't want to just try out it to see what happens because i don't want to send a nuisance call to the emergency services when there isn't an emergency.