Default How to block the notification sound in G pro 2

Hi, Im using the G pro 2(D838) for the last 1 week.After every call i will get the notification of balance from my mobile carrier for the account balance and its coming with a music its weird and i wanna block that sound is that possible ? i have searched the phone in all possible way but didn't got any solution for that. Can some one help me out with this !! Thanks in advance !!!