To find out all the available commands, you can ask "What can I say?" You can also ask "Am I connected?" and the headset will let you know if the headset is connected to your phone, and it'll even let you know how many bars of network signal strength you have. To answer a call you can say "Answer" and to reject a call you can say "Ignore." As a nice bonus feature, you can also say "Call information," which will prompt the headset to call Microsoft Bing's information service. You can then use Bing to find out about local businesses, restaurants, or any sort of information you might like.
Other commands include "Battery level" (it'll tell you the battery level of both the headset and your phone), "Call back," "Redial," "Settings menu," "Phone commands," and more. You can also set speed-dial voice commands for different numbers. Aside from the voice interface, you can use the BF-301v's multifunction button to answer and end calls as well. The BF-301v also has A2DP technology, meaning it can stream music or any other audio from your phone to the headset.
We thought the audio quality was excellent. We made several calls from a few different environments--our CNET office, a moving car, and outside on a busy city sidewalk. We had no problems hearing our callers at all--they came through loud and clear with nary a blip of static. Their voices sounded clean and natural, too.
Callers had a similarly great experience. In the quiet office, they heard us without a problem. In the moving car, they didn't hear any road noise. As for the busy city sidewalk, callers could hardly believe we were outside--they heard a little bit of environmental noise, but it wasn't significant. They could even hear us despite the occasional strong gust of wind.