I had my local dealer look at the mic quality situation. There is a volume adjustment that appears at the bottom of the display screen when you dial a phone number. This adjustment controls the mic volume only. It should be set between 18 and 22. Setting the volume at this level stopped my voice from cutting in and out and folks on the receiving end could understand me much better. However, the quality isn't even close to other hands free units I've used. My brother in law's Prius is much clearer. I think Scion is using a cheap mic. Also one of the technicians speculated that the mic may not be properly matched to such a small car. That the small interior creates feedback accounting for the "hollow, tinny" sound.
If I deleted complaining clients from my Facebook, they would teach me a lesson by going elsewhere.