Samsung Galaxy A3 (2016)
Android 5.1.1
1 Find "Message centre"
Press Messages.
Press MORE.
Press Settings.
Press More settings.
Press Text messages.
Press Message centre.
2 Set the message centre number
Key in +6421600600 and press SET.
+6421600600
3 Return to the home screen
Press the Home key to return to the home screen.