toptobottom,
This probably doesn't help you much (since you already have a headset), but I have a Lightspeed Zulu headset, which comes with integrated bluetooth. It hooks up to my phone without a problem, allowing making and receiving calls in flight. I've never really used this (except once to test, while someone else was flying - "I'M CALLING FROM THE HELICOPTER! NO, THE HELICOPTER!"), but I seem to remember it automatically mutes the call when the radio starts talking.
It also has a discrete line-in socket which I can plug my phone (or mp3 player, etc.) into.