Redsn0w can be used to unlock iPhone 4 for both Linux and Windows. You must choose the right version of Redsn0w depending on the version of the firmware of your device. It is best to have the latest iOS for your iPhone. In tethered unlocking, you do not require a computer for rebooting your device. You have to update the firmware of your phone to 4.2.1. iOS versions above 5 are not easy to unlock and hence are not preferable for unlock.
Once you have got the required firmware on your iPhone 4, you have to download from the internet Redsn0w version 0.9.6b4 or a later one depending on what firmware you have. Launch Redsn0w and then choose the firmware installed by you. Redsn0w then verifies and prepares the data for unlock. Install Cydia after this. Then the iPhone has to be switched off and connected to a computer. The iPhone will enter into DFU mode and then be unlocked by Redsn0w. Here is a step- by- step guide on unlocking your iPhone 4:
* Step 1: Install iOS 5.0 for your iPhone 4 through iTunes
* Step 2: Download the recommended Absinthe unlock solution
* Step 3: Launch the software and then connect the device to a computer via a USB cable
* Step 4: Click on the jailbreak option to start the jailbreak process
* Step 5: There will be prompts on your device. Ignore these prompts.
* Step 6: Absinthe will complete building the data for jailbreak. This may take a few minutes. Wait patiently. On the completion of this action, you will be sent a notification.
* Step 7: Look for the icon of Absinthe or jailbreak on the desktop
* Step 8: Click on the Cydia icon to install Cydia. You may get a database connection error message being displayed. If this happens, close the program and retry.
* Step 9: After the Absinthe installer completed installation, there will be a Cydia icon on the spring board of your device.
* Step 10: click on the Cydia icon and install it to complete the unlock process on your iPhone 4.
This method is preferred over Redsn0w as it is not always successful. There are many disclaimers along with Redsn0w added by hackers, which poses a risk to your device’s safety while unlocking using Redsn0w. The free methods for unlocking require a lot of information or else require a lot of background research to complete. So, it is not advised for first- timers.
The best unlocking software can be obtained from third parties. You have to pay for it but you can go ahead immediately with the unlock process. Also, the software is regularly updated, allowing you to unlock even the latest versions of your iOS. Then, you can use apps developed for the latest iOS firmware for free. Redsn0w is the only tethered unlock, that is, it does not require to connect your iPhone 4 to a computer and can be carried out on the device. Learn more about the iPhone 1 touch screen , iPhone 2 disassembling, iPhone 3 specifications and iPhone 5 iCloud