Voice Call Dialer - Speak to Call is a free Android app that lets you make calls using your voice. The app works by searching your contact list and then calling the person who is named there. You don't need to type the number. You can even use the app while driving, since it doesn't require any input from the driver.

It is compatible with both Android phones and tablets. It has a simple and intuitive user interface. All you have to do is say the voice command that matches the contact name in your contact list and it will automatically be dialed.