Just follow these step-by-step instructions in order to jailbreak your iPhone 4, iPhone 3GS or iPhone 3G device. One thing which is important to note here is that this jailbreak tool doesn’t hacktivate your device. You will need an original supported SIM card to activate your phone with iTunes. (Update: If you do not have original SIM, follow this video guide from RP to activate without original SIM)
Guide to Jailbreak iOS 4.0.1 on iPhone 3,3G,3GS Using JailbreakMe 2.0 (Star)
Backup all your data on the device using iTunes.
Update your iPhone 4, 3GS or iPhone 3G on the latest iOS 4.0.1 firmware with iTunes. Download iOS 4.0.1 here.
Open Safari on your iPhone 4, 3GS or 3G and navigate to http://jailbreakme.com
“Slide to Jailbreak” to begin the jailbreak process.
JailbreakMe will download some files it requires for jailbreaking.
Once the download is completed, it will automatically start the jailbreak process. Wait for it to complete
Once the jailbreaking completes, you will be greeting with a message saying “Cydia has been added to the home screen” Voila! You now have jailbroken your iPhone on the latest firmware!
How to Unlock iPhone 4/3G/3GS on any baseband
Follow this simple step-by-step tutorial to unlock your iPhone using UltraSn0w 0.93 so that you can use it with any carrier you like. It is supported on all basebands upto 05.13.04. Update 1: If JailbreakMe.com doesn’t work for you then you can try out this alternative link: http://jailbreakme.modmyi.com/ Update 2: If you are looking for the guide to Jailbreak iPod Touch 3G/2G using JailbreakMe 2.0 Star, click here. Update 3: Fix for Facetime and MMS issue on iPhone 4 after JailbreakMe Jailbreak Update 4: If you are looking to jailbreak iPad using JailbreakMe 2.0 Star, here is the guide.