As previously noted, iPhone firmware/software revision 1.1.1 makes it impossible to:
- unlock the iPhone for use with carriers other than AT&T
- Install third-party native applications via the instructions in our guide or any other means
- perform call functions with an iPhone that has been previously unlocked
Consequently, if you've yet to purchase an iPhone and would like any of the aforementioned functionality, the time to purchase is now. Currently stocked devices at most Apple retail outlets and AT&T stores have older, 1.0.x firmware revisions installed according to reader reports, but it likely won't be long before Apple replaces the stock with models that carry the updated, un-hackable, unlock-resistant firmware update.
You can check whether or not an unactivated iPhone is running the old firmware version by entering field test mode. Do this by invoking an emergency call, and dialing *3001#12345#* then pressing "Call". Tap "Versions," and you will see the firmware revision (which Apple has misspelled "firware").
If the iPhone has firmware revision 03.12.06_G or 03.14.08_G, it is using either firmware revision 1.0, 1.0.1 or 1.0.2, and can be hacked to install third-party applications as well as unlocked. If it is running firmware version 04.02.04_G or 04.01.13_G, the device has the updated 1.1.1 firmware revision and cannot be jailbroken to allow third-party application installation nor unlocked.
If you've purchased an iPhone with a newer firmware revision, you may decide to return it and seek a replacement with the older firmware installed.
There is no way to downgrade to firmware revision 1.0.x if your phone already has firmware revision 1.1.1. However, if you need to restore your iPhone and want to keep firmware revision 1.0.2 or earlier, follow the instructions in this article.
Also, if you need the firmware file to perform hacking procedures and don't already have it on your machine (or the version of iTunes you are running forces you to download version 1.1.1), you can download version 1.0.1 or version 1.0.2 manually. The AppTapp (Installer.app) installer will download these files automatically.