The voice quality is good for those you call, but at highway speeds the volume in the car is not quite loud enough. I have a quiet Mercedes and I still can't use in on the freeway. It works fine arounds town. I use it with a Treo 680 and it creates a quirk with the phone. After I use the Blue Ant, I need to power off the phone and power it back on or I can't hear those I call with regular phone (no Bluetooth).