With an iPhone firmware update coming this week that could potentially be permanently device-crippling to unlocked iPhones, relocking tutorials are popping up.One of the most definitive, if not yet battle-tested, comes from TUAW (The Ultimate Apple Weblog's) Erica Sadun.
Not without reader feedback (some of it critical) Erica recommends that if you feel the need to relock your iPhone that you perform the following steps:
(Take out your SIM from your iPhone.)--Erica writes she is still checking on this step.
Download the 1.0.2 firmware to your computer and unzip it. It uses a .ipsw extension but your unzip program should still work. Change the extension if you have to.
Extract the ramdisk as such: dd if=009-7698-4.dmg of=ramdisk.dmg bs=512 skip=4 conv=sync
Mount the extracted ramdisk.
From the ramdisk, copy /usr/local/bin/bbupdater,/usr/local/standalone/firmware/ICE03.14.08_G.eep, and /usr/local/standalone/firmware/ICE03.14.08_G.fls to your iPhone.
Place these into a folder on the OS partition (such as /bbupdate) and not into a folder on /var/root. The /var/root partition is set noexec and you cannot run programs from there.
Disable com.apple.CommCenter.plist--either using UIctl or launchctl: launchctl unload /System/Library/LaunchDaemons/com.apple.CommCenter.plist
On the iPhone, navigate to the folder where you stored bbupdater and the eep and fls files. Run bbupdater as such: ./bbupdater -f *.fls -e *.eep Reload comm center: launchctl load /System/Library/LaunchDaemons/com.apple.CommCenter.plist
Reactivate with your favorite AT&T SIM. Erica indicates she personally likes using iASign.
And cross your fingers. This might work.
Then if it does, maybe you've learned your lesson- that you shouldn't have unlocked your iPhone in the first place.