Prepaid Popup Notification

I use a prepaid blackberry connection on my 8830 and whenever there is an SMS, call, etc. a popup notification will appear with a loud beep showing the last call amount and balance left in my prepaid account. I understand it is an operator dependant feature and cannot be disabled. However is there any way to disable the load beep sound? I have checked the profiles and even when using Silent profile the sound is produced. I cross checked that all the sound profiles were set to None including Level 1 message. Please help me in finding out where to disable the sound for that notification.