Bluetooth hands free client volume control

Question

I have an android device acting as a hands free client device using hfp.

Using the following code:

I am able to receive a call and the speakers and mic are work

Answer 1

Could you please try below. I did not try myself but sounds similar problem if I understand correctly:

Android Bluetooth Earpiece Volume

"Android is using int 6 for bluetooth volume and not documented. Just use 6 instead of AudioManager.STREAM_VOICE_CALL and try, It should work"

I assume for you will be to replace AudioManager.STREAM_BLUETOOTH_SCO with 6.

Good luck, I hope it will work.