When you receive an incoming call and the screen is unlocked, tap the Quick msg icon  . If the screen is locked, swipe the Quick msg icon
. If the screen is locked, swipe the Quick msg icon  in any direction.
 in any direction.
Tap the text message you want to send in place of answering the call.
This feature can only be used to send a message to another mobile phone. It is not applicable to incoming landline calls.