Dial *151#
Call number 151.
You can make 1 free request within 24 hours, all subsequent requests are paid and range from $0.5 to $1.0)
Call number 150 and listen to the instructions.
Enter the 14-digit voucher code and press #.
Upon successful crediting, the auto-responder will inform you of the updated account balance.
SMS center setup: Menu -> Messages -> Settings -> Service Center, enter the SMS center number: +882161900000