Hands free app on my Android navigation stereo in vehicle?

[AC Question]

hands free app on my android navigation stereo in vehicle.

I have a samsung s6 smartphone which I connect via bluetooth to my android based navigation stereo in my vehicle. I am looking for a hands free app that can be used on my vehicle stereo so I can make phone calls hands free. I have tried a number of them but they do not here my voice cammands. Thanks Bruce