Call a Contact by Voice Dialing
You can call numbers directly by saying the contact’s name or number.
From the Home screen, tap Apps
> Voice Dialer 
.Say “Call” or “Dial” then a name or a phone number.
Or, you can say “Redial” to redial the last number dialed.
If a list of results is displayed, tap the one you want to use.
NOTE
You can also access this feature by tapping the Voice Dialer Key 
on the Phone application
dialpad.