John,
If you're still having a problem, here's the fix. There is volume control for the microphone that is accessible through a hidden menu. First hold the "info" button (I did it for about 5 secs) then switch your parking light switch from off-to parking lights-repeatedly while still holding the info button....it takes about 4-5cycles...an poof the NAV screen enter yet another Service menu. From there I navigated to a bluetooth menu where I was able to adjust the Microphone volume higher so that people can hear me better! The factory setting is 0 but you can adjust up or down from 1 to 5. You will have to turn off your car to exit the hidden menu. At least that works for me on 2007 ES350.
