BB Bold :: 9900/9930 - LOUD Network Notification Sound

I found out that when I try to dial something in the "Phone" section (Phone icon), there is a sound - how do I disable it?Also I use a pre-paid package, when I check my fone balance, there is always a network notification sound that is REALLY loud (!) and there is absolutely no way to reduce the volume or make it silence.I work at office and I want to silence the key tone when dialing in Phone section, along as reduce sound or silence the network notification sound when check balance.Atm the only way is to switch to Silence or Alerts Off modes.