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Discovery! Baseband now downgrades with OS downgrades!

A

Amino Man

macrumors 6502
Original poster
Aug 25, 2010
301
3
Here's all I did.

1. I restored to 4.1 8B117 (not an upgrade)
2. Looked at my baseband version (it was 02.10.04)
3. Then I downgraded to 4.0.2 by option-clicking restore (successful, no DFU mode)
4. Then I looked at my baseband version again (it was back to 01.59.00!!!)

How crazy is that? As far as I know, iTunes has NEVER done that before in the history of OS updates!

How is this possible? Does iTunes 10 automatically revert the baseband so you can downgrade to any OS you want?

Someone else please try this!

This computer isn't running any mods or host files (whatever that means).

Thanks for viewing.

By the way, I'm not trolling. This REALLY happened. I'm back on 4.0.2 and I didn't have to do anything special except option-click restore and clicked on iPhone3,1_4.0.2_8A400_Restore.ipsw

Please, someone else try this so we know for sure that it works. Please.

Could this be an iTunes 10 thing?
 
Its an iPhone 4 thing, as long as apple is still signing the OS, you can downgrade the baseband. Once they stop signing it (ie, a new one comes out) the baseband is no longer downgradable
 
mackmgg said:
Its an iPhone 4 thing, as long as apple is still signing the OS, you can downgrade the baseband. Once they stop signing it (ie, a new one comes out) the baseband is no longer downgradable
Click to expand...

When do they stop signing it? As long as it's an official firmware, it will downgrade and upgrade?
 
They usually stop signing the previous version a couple weeks after the latest iOS update. So yes as long as Apple is still signing you can downgrade and upgrade as much as you like.
 
draz said:
They usually stop signing the previous version a couple weeks after the latest iOS update. So yes as long as Apple is still signing you can downgrade and upgrade as much as you like.
Click to expand...

With 4.0.2, they kept signing 4.0.1 for a week or so. Normally, they stop signing the old firmware within an hour or two of a new version coming out
 
mackmgg said:
Its an iPhone 4 thing, as long as apple is still signing the OS, you can downgrade the baseband. Once they stop signing it (ie, a new one comes out) the baseband is no longer downgradable
Click to expand...

Is this actually an iPhone 4 thing? Baseband never downgraded on my 3GS.
 
mackmgg said:
With 4.0.2, they kept signing 4.0.1 for a week or so. Normally, they stop signing the old firmware within an hour or two of a new version coming out
Click to expand...

Thank you very much for explaining that to me. I appreciate it.
 
mackmgg said:
Its an iPhone 4 thing, as long as apple is still signing the OS, you can downgrade the baseband. Once they stop signing it (ie, a new one comes out) the baseband is no longer downgradable
Click to expand...

so you can downgrade your baseband with your shsh blobs from cydia?
 
Did not Work for Me!!

Tried this several times last night after I heard the news. I cannot downgrade back to 4.0.2 using apple (not saurik) servers. Does anyone know if apple is still signing 4.0.2?
 
djpatrickp said:
Tried this several times last night after I heard the news. I cannot downgrade back to 4.0.2 using apple (not saurik) servers. Does anyone know if apple is still signing 4.0.2?
Click to expand...

I guess they're not signing it anymore. Sorry.
 
You can only downgrade the baseband on the iPhone 4 in the very limited window where Apple is signing both 4.0.2 and 4.1. The iPhone 4 baseband now has a signature check but, unlike the firmware signature check, it's randomly generated with every restore so there's no way to save them for now.
 
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