Hi,
A cell phone on a bike, I got one. It's just for emergencies so I keep it in a hard shell case in my panniers. Someone like Lance wears his clipped to
his shorts and wears earbuds. He hates phone calls while riding, sometimes being a millionaire sucks. Which brings me to my thought. You couldn't use your idea while riding. And stopping to use the phone is a drag. I think I'd rather throw it into a pocket.
Less likely to lose or forget it.