This issue happens for both Voice Control and Phone calls where the usb output will get cut off and no longer a valid route, then when the phone call is finished the audio will revert back to usb (Car Head Unit). I have tried tackling this for a while now and I only wish to achieve this so I can answer a call while docked in my car or make a voice command and hear the result via car speakers. Other wise i cant hear anything as my phones loud speakers are kinda dying... I have hooked MobilePhone.app -> AudioDeviceController and through some logging, even though the usb connection is in, _pickableRoutes will never return a usb connection (Only reciever or speaker). I also find from a log for a VoiceControl (Can't remember which class, i think SBVoiceControlAlertDisplay) but I logged a method which displayed that it used a PhoneCall class during its audio routing methods. Has anyone had experience with this? Could anyone point me to the right area to explore? I have been at this for way too long leading me too ask for help!