I would just avoid it altogether.

IF I somehow get a call or need to make a call, I'll find a place to pull into and take care of it. I just look at is as one more distraction that you don't need...for the sake of safety. As far as music goes, I'll take my cell phone and start the music player before I begin my ride and zip it inside my jacket's chest pocket. It is audible enough for me to hear it yet not so loud that I can't hear the traffic.