See iPhone Dev Team site for all the information you will need, its free and easy - dont buy anything from anyone they are only selling what the iPhone Dev Team gives away for free!
First you need to edit some iTunes settings to allow the custom ipcc file to be installed, with iTunes closed do:
Mac - open a terminal and type in..
defaults write com.apple.iTunes carrier-testing -bool TRUE
Windows - open up a command shell and type in:
"%ProgramFiles%\iTunes\iTunes.exe" /setPrefInt carrier-testing 1
Next start iTunes, connect the iPhone, hold the shift key while clicking restore button, change file types to ipcc and select the ipcc file you downloaded - Reboot the iPhone and enjoy!
This will configure and enable, MMS, Tethering, APN Internet Access, Planet 3 Bookmarks, Custom Operator Logo, Voicemail (Not Visual), Disable Call Forwarding Active Notification.
