FM Transmitter/Hands free

[kp99]

I've set my directions and music to be heard through my car speakers via FM Transmitter but if I want to place a call, it will dial through my phone and I can't use tt for the conversation. If I set my directions/music/hands-free through the internal speakers, than I'm able to use tt for hands-free perfectly fine. Has anyone else had this problem? How can I solve this as I prefer the directions/music through FM transmitter and hands-free through the internal speaker?