I used it for remotely unlocking the doors once, that was scary to think they can unlock your doors from anywhere and open the microphone and listen in with police approval of course. I guess now they can even shut down the engine if it is reported stolen. But when they went digital I never had mine upgraded, but I don't think I will pay $90.00 for a storage compartment
If money is no object try researching Bluestar that uses the microphone and speakers for cell calls.
http://www.costartech.com/pb/products/bluestar.html