Did you have the Parrot and OnStar connected to your Symphony or only OnStar? They are using the same phone pins on the head unit and unless to connect both to the phone mute/NF+/NF- pins at the same time, either of both won't work. I think I read once on AW that someone used the Navi mute/NF+/NF- on the Symphony for his phone kit while OnStar was connected to his phone pins. But the RNS-E has no Navi pins anymore, so that's ot an option. You may be able use some relay which uses the mute wire to connect either of both to the phone pins. Just a thought.