ATM Pin Reversal

I don't know this, but for sure, is really good to know.
If you should ever be forced by a robber to withdraw money from an ATM machine, you can notify the police by entering your PIN # in reverse. For example, if your pin number is 1234, then you would put in 4321. The ATM system recognizes that your PIN number is backwards from the ATM card you placed in the machine. The machine will still give you the money you requested, but unknown to the robber, the police will be immediately dispatched to the location. This information was recently broadcast on CTV by Crime Stoppers however it is seldom used because people just don't know about it.
I tried looking for related video in Youtube but couldn't find...