(Phone4 is perfect. You need to use the newly released RedSn0w Yue/yu tool. During the upgrade, the baseband may be upgraded, so please keep the baseband if there is a lock. The more important it is to use self reliant firmware to upgrade, the more important it is to download the device firmware corresponding to iOS 5.0.1, and the RedSn0w0.9.10b1/yu tool. (If your device is already iOS 5.0.1, you do not need to download firmware))