have you ever called 911?

I personally haven't ever done it. I think I may have called 911 once when I was five as a prank call or a dare, something of an unserious nature, and then I froze and said nothing into the phone receiver. I was there when my father called 911, though; my sister had fallen from the roof (strange, yes, I know) and we called an ambulance as soon as we saw her fall.