Just because I spent so much time looking for this last night and found so many broken carrier data files, I figured I’d keep this around for me.
Instructions
- Make a backup of your /Library/iTunes/iTunes Carrier Support/ATT_US.ipcc file.
- Quit iTunes
- Open Terminal and type “defaults write com.apple.iTunes carrier-testing -bool TRUE”
- Open iTunes, select your phone and press “check for updates” while holding down the ‘Alt’ key on your keyboard. You will be prompted to select a file. This is the one that worked for me after numerous other failures. (found in gizmodo’s cache somewhere)
- After you load the file, make sure you restart the phone
Instructions for Windows are the same, but you’ll have to use the Windows Paths for stuff (C:\Program Files\iTunes\blah blah blah).
Right, and I’m not responsible for you running up a trillion dollar bill with AT&T or if your spine curves or if your teeth yellow or if you drink rat poison because you fell in love with a rough trick named Jim or anything else as a result of you trying to do something to your bejebus phone 
John Case says:
Wyatt,
15 August 2009, 6:14 pmA friend of mine showed me how to setup tethering on my iPhone. On the phone, point the browser to http://help.benm.at. Scroll down the page until you see the “Tethering & Internet Settings” section. Very quick and easy install.
Wyatt says:
That’s correct. I’m just a little funny about random websites updating my phone’s information without me getting to look at it first. Guess I’m paranoid that way
16 August 2009, 5:42 pm