5. in order to unlock your iPhone you will need to search for and download the following baseband bootloaders:

3.9 baseband bootloader
4.6 baseband bootloader

We took the liberty to find the basebands for you. You can find both baseband bootloaders on iPhoneFreakz.com.

Just scroll down to "Boot loaders"

Like the .ipsw file before, be sure to download the files without unzipping them.

Return to redsn0w and navigate to the .bin files you just downloaded.

To learn more about baseband bootloaders check out this forum posting on the Hackint0sh site.

6. Turn off your iPhone. If your iPhone isn't plugged into your Mac, plug it in first, then turn it off. Once your iPhone is off and plugged in, you can continue.

Hold down both as instructed by Redsn0w

Before you press next, prepare yourself. Redsn0w will ask you to place your iPhone in DFU mode. To ready yourself, grab your iPhone and place your fingers above the Top and Home button.

Press next.

Just follow the Redsn0w directions to put your iPhone in DFU mode and you'll be fine. 

7. Once the iPhone boots into DFU mode, redsn0w will do its magic. You'll see a series of screens that inform you that Redsn0w is Uploading ramdisk, Uploading kernal, Rebooting and finally done.

While this is all happening, your iPhone will reboot a few times and run the BootNueter app. Do not interrupt this process. 

Your iPhone will finally boot up normally and will be ready for a new SIM.

Unsure how to replace the SIM on your iPhone? Check out our how-to. 

That's it. You are now the proud owner of an unlocked iPhone 2G. In order to keep your precious iPhone unlocked, check with the Dev-Team blog before updating the iPhone OS in the future. Some updates are fine, while others will restore your iPhone to it's locked status. 

Pre-Paid T-Mobile

There are two major GSM carriers in the US, AT&T and T-Mobile. If you unlocked your iPhone to get away from AT&T, the choice is pretty simple. 

We went to the mall and purchased a pre-paid T-Mobile SIM. You can sign up with a proper monthly based T-Mobile account with data and enjoy most of your iPhones features including an unlimited text and data plan for $19.95 per month. T-Mobile is surprisingly iPhone friendly here in the United States even though they don't offer the iPhone. A quick search on T-Mobile's site will show you how to set up internet and email on your iPhone. 

Here are T-Mobile's settings for mobile internet on the iPhone:

    1.    On your iPhone navigate to  Settings > General > Network > Cellular Data Network
    2.    Select the APN field, and enter internet2.voicestream.com.
    3.    Tap return.
    4.    In the Username field enter (this may be intentionally blank)
    5.    Tap return.
    6.    In the Password field enter (this may be intentionally blank)

If you plan on traveling, you can purchase pre-paid SIM cards from carriers all over the world. Suddenly, you're a just a little bit more international. 

Our T-Mobile iPhone wasn't without issues. Check out what worked and what didn't. 

What works -

iTunes syncing and installing apps - All of our apps still worked and iTunes recognized our unlocked iPhone without any problems.

Voicemail - When you receive a voicemail, you'll receive a red dot, not a number. But it works.

SMS - As long as you don't want to add Emoji or images, you're cool.

Find My iPhone -Locate your iPhone via the MobileMe feature. 

What doesn't -

MMS - This has to do with Apple not placing adding MMS to the 2G iPhone version of iPhone OS 3.0.

Visual Voicemail - Even though T-Mobile is the official iPhone carrier in other parts of the world, don't expect Visual Voicemail to work here.

Emoji - You can't send or receive Emoji images via text message.