I havent really looked deep into this issue yet but while sitting in my vehicle with my phone bluetooth connected to my 4runner dictation in imessage will not work...When I turn off bluetooth it starts working again, so i assume the iphone hands off microphone operation to the vehicle while connected? I know when i get a call I can either use the phone or just speak out loud and the vehicle picks up conversation. any solution to this or is this working by design?