How do I answer a phone call in Nokia N97 when the device is locked?

When the Nokia N97 or N97 mini device is locked, the phone call can be answered by swiping the Answer (or Swipe to answer) arrow on the touch screen in the direction of the arrow.

For more call options, the device can be unlocked by swiping the Unlock (or Swipe to unlock) arrow or by using the lock switch.