Is it having a remote control car lock system??
Assume that you have locked your car parking it somewhere far from home. On the next day when you wanted your car, you have gone there leaving the remote lock at your home. Then How-to open the car door?? The solution is quite simple if you have cellphones, one with you and one at your home.
** Just call some one at home at his/her cell phone and ask for the duplicate keys.
** Now, as usual the key chain of duplicate key would also be having the remote control, so ask the person at home to press the unlock key on the remote.
** While the person presses the unlock key hold your mobile phone about a 10-12 inches from the car door.
** The unlock signal will travel on the cell phone network and your car will be unlocked.
This amazing trick have been tested on many cars and is found working in almost 90% of the cases. Try it yourself and post in your valuable comments.