André wrote a nice article on how to disable the annoying message you get when you call  someone or even when someone calls you. Well, the article isn’t really about that but rather tethering. Nevertheless, thanks to Michael, I know now that a side-effect of setting this up, is that the call forwarding message disappears.

If you’re German speaking, just visit André’s (more detailed) or Michael’s (additional information) article and follow the steps. Otherwise, just read on:

1-a) Mac OS X: Close iTunes, open the Terminal and type (copy/paste) the following:

defaults write com.apple.iTunes carrier-testing -bool TRUE

1-b) Windows: Close iTunes and type (copy/paste) the following into Start -> Run

%ProgramFiles%\iTunes\iTunes.exe /setPrefInt carrier-testing 1

2) Visit this website, scroll down to the table, choose your carrier and download the *.ipcc file.

3) Connect your iPhone via USB and start iTunes.

4) Now press Alt (Mac OS X) or Shift (Windows) and search for updates. A new window will open, where you choose the just downloaded file.

5) You don’t get much response from the system (or at least I didn’t get anything), but it sure works.