B U L L S H I T ! ! ! !
A cellphone is designed to carry a low-fidelity sound wave which is captured, converted to a digital signal, sent via microwave and then re-configured on the other side as a sound wave.
You are confusing a wave form (which acts on the microphone) to the signal given off by your transponder which is a form of electromagnetic radiation (Either far IR, Radio or MW). Cellphones are not, have never been, will never (M.T.L.) be designed to pick up, decode, transmit and emit other forms of EM radiation. (With the exception of those who use proprietary blue tooth or IR or WAN but this will talk to a key fob about as well as a laptop will and these functions are NOT designed to go over air only locally)
Next you'll tell me that the BEEPBEEP sound you hear is what actually unlocks the car and that there is a Swiss kid who has learnt to yodel this sound and can open any car if you squeeze his balls (actually this is more likely than your cellphone story)
I'm guessing that when you say "you" did this twice, you were actually tricked by the same person twice who phones a friend while he pushed the key fob in his pocket.
If you STILL believe this bollocks then I have some really bad news for you regarding Santa Claus, The Easter Bunny, The Tooth Fairy, that email you just got from The British Sweepstakes about your 1 Billion Pound Prize and that "4 weeks to penis enlargement" book you are currently reading.... then again, maybe I should just sell you some property. It's a guaranteed investment... really

HELLAS said:
I have personally done it with a 2004 325i and a 2003 Merc CDi. :thumbsup:
Images of Hellas with his wanger up the tailpipes....