IP 500 running 5.0.8 with a PRI using a external music source. When calls internally from extension to extension or using a music button the on hold music plays clear. On incoming or outgoing calls when the caller is placed on hold the music then has static. I have checked the input cord for the music on hold and changed cord to a new one and changed the input device from a radio to a output on a sound board of a radio station. This customer of mine is a local AM station and off of the sound board connection to the ip office i am clear no static anywhere. What could be causing this?