Hmmm... you know, I'll bet that a few people have died while trying to contact 911 because they couldn't find the "11" key.
When I trained as a CPR instructor we were taught to teach our students that it is
always nine one one precisely because, just as there are documented cases of very young kids saving the day by dialing 911, there are also documented cases of junior finding the nine and not the eleven.
Another "OH! For..." element was the need, prior to caller ID and autolocate software, to be able to give your location with some precision. The backup story in the class was of a guy at a friend's house for Monday Night Football when the friend went into arrest. The had been doing the Monday thing for years, could and had driven and walked to and from his friend's while very drunk, but could not give an address or cross street. Exit friend.