Galaxy S4 phone audio with ibolt car mount

I can't get the phone audio to come out the ibolt microusb connection that has a USB power connection and an auxiliary cable plugged into radio.

I can get music to work fine, just not an actual phone call coming in. I have to disconnect every thing instead of just listening through the car speakers.

I can send audio to the car dock. The problem is that the car dock itself determines what audio can go to the 3.5mm cable and what cannot. There is no way for me to override this.

It seems all the car docks I've read about do the same thing. I'm guessing it is a feedback issue where the audio from the car speakers and the mic on the phone can't be dynamically calibrated to prevent feedback.

This iBolt page says (NOTE: phone calls not routed to car-speakers due to Samsung firmware limitations.)
http://www.iboltshop.com/xProDock-Active-Samsung-aux-out-car-speakers/dp/B00AOCSFYC

I've seen many other post about this issue:
http://forum.xda-developers.com/showthread.php?t=2024812

http://forum.xda-developers.com/showthread.php?t=2024812