To display the Ignore with message option on the incoming call screen, enable it in the Settings menu.
From the Home screen, tap the Phone icon > the Menu icon > Call settings > tap the Allow ignore with message button .
If the screen is unlocked, tap the Ignore with message icon .
If the screen is locked, swipe the Ignore with message icon 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. You cannot send messages to landlines.