Number 9, 911
It was around two in the morning when the phone rang. The caller was a great friend from PA who, knowing my unconventional hours, doesn't hesitate to call, even when most are asleep.
We chatted sewing machines for around half an hour when she suddenly changed tack and announced that a police car had arrived at the front drive. Now, this friend's nearest neighbour lives some miles distant and the car was obviously targeted at their address. She left her husband to deal with the law and we chatted on. A couple of minutes later another police car turned up and her husband shouted up the stairs for her to come to the door.
We terminated the call with me saying I'd get the next plane and post bail if necessary.
It was all quite simple really. The code for international calls from the USA is 011. My friend dialed this, but then decided she might have mis-dialed and hung up and started again. She had miss-dialed. Using an old-fashioned rotary dial (all my friends are like this) she had failed to drag the dial around all the way for the first digit. Instead of a zero she got a nine and thus dialed 911.
The emergency services noted the attempted call and then, when they traced the number and found it engaged, thought that the phone might have been ripped out of the wall by a burglar, drunken husband or worse. The police went into action and surrounded the house.
My friend's husband had to display her, in one piece and not bleeding, before they accepted that the whole deal had been a mistake.