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iPhone 3G 3.1.3 firmware -- downgrade baseband from 06.15.00 to 05.13.04

peterboxer

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I have an iPhone 3G locked to AT&T, am trying to unlock it to move to T-Mobile. I followed the instructions on whited00r.com, but ran into some problems.

My original firmware was 4.2.1 with baseband 5.15.04. I used Redsn0w 0.9.14b2 to install iPad baseband 06.15.00. After this I was unable to go any further, I kept getting various iTunes errors. So, I downgraded the firmware to 3.1.3 by connecting the phone to my laptop, running TinyUmbrella, ran TSS server, used iTunes to Shift+Restore the 3.1.3 firmware. At this point I had an iTunes error 1015. I then exited iTunes, used TinyUmbrella to Exit Recovery, disconnected from the laptop, inserted the T-Mob Sim, reconnected to the laptop, ran iTunes and the phone was activated and unlocked.

The phone works but data is very slow, even when connected to WiFi, so I figured I should downgrade the baseband to 05.13.04 to improve performance and get back GPS. The problem is when I use RedSn0w 0.9.14b2 to downgrade it says my IPSW (3.1.3) is incompatible. On the other hand, if I use an older version of RedSn0w (e.g. 0.9.2) it is compatible with the 3.1.3 IPSW but has no option to downgrade the baseband.

So, what route can I take? Should I upgrade my firmware back to 4.2.1 via iTunes? Will it let me do that (I don’t have any saved blobs etc), and even if it does will I run into other issues – iTunes errors or phone locked again? Is there some other way to downgrade the baseband?

Any help/advice is greatly appreciated. Thanks.

PS -- when I installed the 06.15.00 baseband I must not have checked "Install Cydia", since I don't have Cydia on the phone now, but it still is unlocked.
 
I've deleted the second thread started by you for this same topic. Besides fragmenting any resulting conversation, making it hard to follow, multiple posts on the same topic are not allowed under our rules.

scifan57, iPhone Forums Moderator
 
Sorry about that -- I wasn't sure which forum to post in, so opted for both. Thanks for cleaning up.
 
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