The cell phone idea would only work if the fob was transmitting an audio signal/tone. Listen to your fob for an audible tone, if yours is like mine you won't hear one because the fob sends a digital signal via radio frequency. The cell phone can only "hear" an audio tone.

Tom
San Diego, California
2007 Nissan Altima Hybrid
Radiant Silver - Black Leather
Technology Package
Purchased 5/26/2007