ACTION_CALL and ACTION_DIAL

There are two intents to call/start calling: ACTION_CALL and ACTION_DIAL. ACTION_DIAL will only open the dialer with the number filled in, but allows the user to actually call or reject the call. ACTION_CALL will immediately call the number and requires an extra permission. So make sure you have the permission

<uses-permission android:name="android.permission.CALL_PHONE" />