It only works with the screen open, and you need to speak into the phone's mic not the bluetooth headset.
Are you saying that even with a bluetooth headset I have to speak into the actual physical phone to give it voice commands - that I can't talk into the bluetooth headset? If so, isn't that pants??!?
I tried the built in voice dial software and so far that has two major advantages that I can see: -
1. It works with the lid closed.
2. It works fine through my BT headphones (HT820).
I can add voice tags to start applications (e.g. music player, tom tom) and also for given contacts for phoning. Okay, I can't do things like check my appointments or skip tracks and so on with the built in application but for car use where all I really want to do is make calls whilst the phone is shut up safe in my glove compartment it works a treat.
Anyone using MS Voice Command successfully through a BT headset?
I'd rather be defenestrating chaos mages...