I do a lot of water sports, and lately id like to do them while im on call for work. I have a aqua-pac water proof case for my iphone that i can strap to my arm, i do not however have the nads to strap my iphone to my arm, then go windsurfing with it at 20+ knots, frequently falling at high speeds. I thought, maybe i can get a small, old almost disposable, hershey bar att phone, then put it into the aquapac, and strap that to my arm and feel as though if i get a call from work, it will ring, or function in case of an emergency. while leaving my iphone in the car. once im done, swap the card back into the iphone. will this work? can you guys recommend an almost 'disposable' att phone?