This is a very interesting legend that’s doing the rounds. It says that if you type your pin in reverse order when you are forced to take money from an ATM, it will automatically trigger an alert to the police. A wonderful technology, isn’t it?
Is it technologically possible?
Yes, most of the hoax slayer websites say its definitely possible. Check out the links below
http://www.hoax-slayer.com/reverse-pin-ATM.shtml
http://www.snopes.com/business/bank/pinalert.asp
They say that there are possibilities of having such setup but the US legislation hasn’t allowed the use of this technology. In fact, there is a guy by the name Joseph Zingher, who has patented it.
Quoting snopes.com here
The reverse PIN system was first imagined in 1994 and patented in 1998 by Joseph Zingher, a Chicago businessman. His SafetyPIN System would alert police that a crime was in progress when a cardholder at an ATM keyed in the reverse of his personal identification numbers. The flip-flopped PIN would serve as a “panic code” that sent a silent alarm to police to notify them that an ATM customer was acting under duress
Is it possible in India?
Nope. Definitely not. Here is an article from Economic Times that snubs this hoax.
Logical explanation
What if, you have a palindromic ATM Pin? For instance, if your pin is 7337, you will have police every time you pick up cash in your nearest ATM. Wow, it would be wonderful to pick up cash with such security 🙂
Still not convinced? Try it for yourself before sharing it on your Facebook wall 🙂
Desi Snopes 
This picture / video shot is from an atm-robbery in Karachi, Pakistan!