To place a call by speaking

From the Home screen, tap the Apps Key > Voice Dialer .

If you have a Bluetooth headset that supports “voice-recognition” or “voice dialing,” you may be able to open Voice Dialer by pressing your headset’s main button or in some other way, and dial by voice using your headset. For details, see the documentation that came with your headset.

Say “Call” followed by the name of the contact or say “Dial” followed by a phone number.