It might be an extra when you add any of the phone options. Perhaps the best is just to try it
on your steering wheel on the right, just below the volume + & - is a button with a stylized face on it. Press it and teh F20 should talk to you and ask you to speak your command
It's far from perfect though...
BTW - didn't you get an explanation of your car when you got it? I got a course of about an hour.