Want to jailbreak and unlock but need to know how to tell what bootrom your iPhone 3GS is running? There are two numbers in your settings that will be a dead giveaway as to what bootrom your phone has. You’ll need to know how to determine your bootrom in certain situations if you want to achieve a software unlock.

1. Open up Settings

2. Tap on General

3. Go to About
4. If you scroll down a bit you’ll see your serial number and your model number.

You can use one of these two numbers to determine if you have an older or newer bootrom.

Model number method

The easiest of the two is the model number. If your model number begins with MC, you have a newer bootrom. As you can see above, my serial starts with an MB. I have an older bootrom.

Serial number method

Another way you can check is by looking at the 4th and 5th digits of your serial number. If it is lower than around week 35, your bootrom is older. I’d say the model number method is the most efficient but you can use both to determine your bootrom version.

If you have other jailbreak questions or run into issues, check out our jailbreak and unlock forums as well!

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iClarified is reporting some very unsettling news for those of you looking to pick up a new iPhone 3GS as they say Apple is now shipping iPhone 3GS devices with a new bootrom blocking the 24kpwn exploit. Devices with the iBoot-359.3.2 bootrom began shipping last week and are now being sold in Apple and AT&T stores. This means if you are unfortunate enough to land one of these new devices you will not be able to jailbreak until the Dev Team or George Hotz can come up with a solution.

For those of you who can’t wait to jailbreak your new iPhone 3GS, we suggest you listen to iClarified and try to pick up a refurbished unit or try to locate some older stock. The race is now on, who will be the first to find a new exploit to take advantage of – George Hotz or the Dev Team?

The cat and mouse game has just got a bit more interesting…

[Thanks for the tip mysterio!]