How do I Adjust the Volume of the Bluetooth Phone in ECO?
You can adjust the input and output volume of your calls.

Input Volume
If you have trouble hearing the person who is talking to you, turn this volume option up. If the person's voice is too loud, turn this option down.
Output Volume
If the other person is having trouble hearing you, turn this option up. If the other person says your voice is too loud, turn this option down.