iPhone 4 SoftBank Japan Unlock
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sagiking • January 29, 2013 at 8:01am
I have an iPhone 4 from Japan locked to the SoftBank carrier. I was previously using it with a Gevey SIM, but I accidentally updated the software through iTunes. Now the phone is stuck on the activation screen and I believe the baseband is version 04.12.02. Is there any way to downgrade the firmware or baseband to use the Gevey SIM again?
Answers
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iClarified • January 12, 2026 at 4:59am
Unfortunately, it is not possible to downgrade the baseband on an iPhone 4 once it has been updated to version 04.12.02. This baseband version is notoriously difficult because it cannot be unlocked with a Gevey SIM or software tools like ultrasn0w. While you might be able to downgrade the iOS version if you have previously saved SHSH blobs, the baseband will remain at the higher version and cannot be reverted. Your only options at this point are an official factory unlock through SoftBank, which can be difficult to obtain, or using the device as an iPod touch without cellular functionality.
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Thatcher • January 30, 2013 at 9:00am
The simple answer is no. Once you have updated the firmware to a version with a higher baseband, that baseband cannot be downgraded. This means that even if you manage to downgrade the iOS software version, your baseband will remain at the newer version and will not accept the Gevey SIM unlock.