poor voice quality using bluetooth

I"ve got a 2008 Prius. I use bluetooth which works fine as far as the connection goes and features go. However, the quality of the reception is really poor. People I'm speaking with via bluetooth are always telling me they can't understand what I'm saying, so I have to terminate the bluetooth connection and speak directly into the cellphone.

Does anyone else have this problem? Does anyone know how to get decent quality reception using bluetooth on a Prius with their cellphone?

 

thanks for your help. I went to that link and found out how to adjust the volume. Hopefully that will help.

Thanks again.
Sheldon