I know how to get access of the PA system with a phone in the office. my goal is to play music on the last day durring the last period. so my original idea was to take a cordless phone have the base hidden in the office and remove the mic in the phone to solder in leads for a 3.5mm stereo jack to my mp3 player. will this work or do i need to build my own circuits to send and recieve a RF signal. I'm hoping to keep the costs minimal because a electrical engeneering degree won't be cheap to pay for and i'm only making minimum wage.