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

Discussion in 'iPhone Unlock' started by Peter Boxer, Aug 10, 2014.

  1. Peter Boxer

    Peter Boxer New Member

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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.
     
  2. Europa

    Europa Moderator
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    Privately unlocking phones is legal now. I would just buy an IMEI unlock on eBay. They are permanent and far superior to the type of unlock you are currently trying to do.
     
  3. Peter Boxer

    Peter Boxer New Member

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    Thanks. I guess I could have done that, but the phone is already unlocked now, so what I really need is a way to downgrade the baseband, hopefully someone can help with that.

    By the way, I can't find any truly "cheap" IMEI unlock on eBay. Lowest is about $20, hardly worth it for an old phone like a 3G. I keep reading about a reputed seller (Unlock Fusion) with a price around $5-8, but can't find them anywhere on eBay.
     
  4. Europa

    Europa Moderator
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    It will take some time before the prices come down. They just passed the law last week. They were only $5 when it was legal last time, so I'm guessing they will get back down to that price eventually.

    I'd update it to 4.2.1. You don't need blobs to go to the last supported firmware.
     
  5. Peter Boxer

    Peter Boxer New Member

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    Great -- thanks for your quick replies! I'll try the 4.2.1 update and will report back.
     
  6. Peter Boxer

    Peter Boxer New Member

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    OK, so I did an upgrade of the firmware to 4.2.1 today. I didn't try using the stock 4.2.1 since past experience showed that iTunes would not restore it since it didn't like the 6.15.00 baseband.

    Rather, I used a custom firmware found via a youtube video (I'm not allowed to post the link, but if someone needs they can search for "How to restore firmware 4.2.1 on baseband 6.15 6.15.00 iTunes error 1015 3g 3gs only" ) and it worked, iTunes restored it without any problems, gave me a "Congratulation, your phone is unlocked" message and then activated the iPhone (had to unplug & replug it in).

    Even some of the prior problems seem to have gone away or at least improved -- I now can get my mail via the mail app, Safari is faster etc.

    Also, GPS seems to work, even though I had thought the 6.15.00 baseband disabled the GPS. Maybe it is not GPS, rather triangulating from cell towers, I wonder if anyone has a view on this. This part (GPS) is no change -- it also "worked" before I upgraded my firmware, even then I was not sure if it was true GPS..

    I still have a few questions:

    1. How/why did the phone get unlocked? I have not installed Cydia nor run ultrasn0w. Is it just because the baseband is 6.15.00?

    2. Will there be a benefit to downgrading the baseband to 5.13.04 -- Safari is still quite slow and I'm not sure if I am getting true GPS.

    Thanks as always and hopefully this update might help others.
     
  7. Europa

    Europa Moderator
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    1. It sounds like the phone was IMEI-unlocked at some point after the iPad baseband was applied, which is good since it's a better unlock and doesn't cause problems with future upgrades or restores. IMEI unlocks are permanent and equivalent to factory unlocks. ultrasn0w with the iPad baseband causes various problems and interferes with restores, so it is an inferior unlock. You'll get the congratulations message in iTunes after each restore with an IMEI unlock and it will remain unlocked without any work on your part, unlike the iPad baseband method.
    2. Yes. You don't need that baseband anymore, so there is no point in dealing with the problems it causes.
     
  8. Peter Boxer

    Peter Boxer New Member

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    Well, I'm the one who installed the iPad baseband and I know I did not do any IMEI unlocks, so it remains a bit of a mystery, not that it really matters at this point.

    I did try to downgrade the baseband to 5.13.04 but despite following the instructions very carefuly and trying several times (including with 2 different versions of Redsn0w) I could not get it to work, so I guess I'm stuck with 6.15.00, unless someone has any suggestions.

    Is there a way to know if my GPS is really working? My maps do work and show my current location, and I even took a picture and it has geotagging, but does that definitely prove that the GPS works, or could all that happen just with tower triangulation? If I am moving it certainly does not update my position very well (very slow to do so), which might be a GPS problem or some other issue?

    On a related subject I also have an iPhone 3GS which I want to unlock (although I think it would have to be tethered, since it seems I have the new bootrom). If I do go ahead and jailbreak and unlock it, will that prevent me from doing an IMEI unlock in the future, whenever I can find a reasonably priced one on eBay?

    Thanks.
     
  9. Zeusz

    Zeusz New Member

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    Alright, hi guys.

    I have similar problems with the OP.

    So I have an old device that is currently running iOS 3.1.3. The baseband is 05.15.04, and unfortunately bootloader is 05.09, so as far as I understand I am pretty much stuck here, and cannot downgrade the baseband to apply ultrasn0w.

    Is there a way for me to unlock AND stay on 3.1.3? Or I just have to get used to the idea of upgrading to iOS4 -- which I don't want due to performance issues?
     
  10. Europa

    Europa Moderator
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    If your carrier won't unlock it, just buy an unlock on eBay. They are permanent and there aren't any hoops to jump through like there are with the iPad's baseband. They cost $30 right now.
     

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