keyless entry and cell phones

[unlucky513]

so my buddies and i are sitting around last night, and my buddy gets a call from his brother saying that the keyless entry (for locking/unlocking cars) can be used over a cell phone. like if you're out of range, the cell phones will carry the signal to the car...

so my friend went out by the street where his keyless entry would be out of range.. he pressed the keyless entry button and nothing happened, his car didn't lock/unlock. so he calls my friend who is in the backyard next to his car, and pushes the keyless entry into the cell phone while my buddy holds his cell phone near the driver's side door, and his car unlocks.

i was kinda shocked that it'd actually work. how does it work?

also, putting your keyless untry up against your jaw will make the signal travel farther.