Tethering with O2 Germany impossible due to apples ipcc files iPhone

Luckily i Germany T-Mobile lost their exclusivity to sell the iPhone. Since this time apple provides new ipcc files over air which I accepted unfortunately. Since this time I lost my tethering functionality again even if my provider O2 allows it. The only way to fix it is to download old ipcc files and to install them via itunes (to do so you need to type the command defaults write com.apple.iTunes carrier-testing -bool TRUE in the terminal (MAC), than resart itunes, press alt+searching for updates, select the downloaded ipcc file and thats it. After that the iPhone is using the unknown-profile. So you have to re-enter the apn and so on, but tethering will work. But again you will see the message Rufumleitung aktiv if receiving or doing a call... So you never can have full functionality it seems.
But why Apple provides wrong ipcc files? And why does Apple not fix own mistakes immediately?
Message was edited by: HumanBerlin
iMac iPhone 3.1-Italy