Not even a week after iOS 4.2.1 was released, and following the update of the RedSn0w jailbreak, the Dev Team delivered today an update to their UltraSn0w unlock for iOS 4.2.1.

This unlock will work for the iPhone 3G or iPhone 3GS with baseband 04.26.08, 05.11.07, 05.12.01, or 05.13.04. It will also work with iPhone 4 with baseband 01.59.00…

For most of you, this unlock will be a little “special” and won’t be as simple as downloading UltraSn0w from Cydia. Unless you’re on one of the above mentioned basebands, you will first have to update your baseband to 06.15.00, which is the same baseband used by iPad iOS 3.2.2. This can be done using an updated version of PwnageTool (see our tutorial), or RedSn0w (see our guide).

This is for iPhone 3G or 3GS only. You will not be able to update your iPhone 4 to baseband 06.15.00. Only an iPhone 4 on baseband 01.59.00 can be unlocked so far.

Once updated to 06.15.00, you will then be able to download UltraSn0w and unlock your iPhone.

This unlock comes with a few downsides though:


  1. There is no way to come back down from 06.15, and there’s no hiding the baseband version from Apple.  You’ll be voiding your warranty in a very obvious way.
  2. If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
  3. Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail).  You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).

Certainly don’t update to 06.15 if you don’t need to!  Only do this if you need the unlock and you’re stuck on 05.14 or 05.15, and you’re willing to assume the above risks.

I highly suggest you read this blog post on the Dev Team’s blog to learn everything about this unlock.

In short:

  • You can only unlock an iPhone 4 that has baseband 01.59.00. You can unlock using UltraSn0w. If your baseband is different from this, you will not be able to unlock at all, since you cannot downgrade or update the baseband.
  • If you have an iPhone 3G, you can unlock iOS 4.2.1 using PwnageTool.
  • If you have an iPhone 3GS with an old bootrom and are already unlockable but want to update to 4.2.1, please wait for the Dev Team to release an “unofficial” bundle for you that will get you to 4.2.1 but preserves your baseband.
  • If you have an iPhone 3GS with an old bootrom and already on 4.2.1, use RedSn0w.
  • iPhone 3GS users with old bootroms who want to go to 4.2.1 should not use PwnageTool. You should update to stock 4.2.1 first, then use RedSn0w to update your baseband.

Check out our PwnageTool tutorial or RedSn0w guide to show you how to update your baseband.

  • Brianna

    I’m pretty sure I did, I neglected to mention that I’m on T-mobile so the phone wouldn’t be working at all if it hadn’t been unlocked…should I still run it?

    • Brianna

      I re-ran it, still not dialing out. No apps installed, could it be a package on Cydia causing this? I re-jailbroke it for a second time and there was no difference. The only packages I have installed are “Bigboss’s Source”, “Cydia Community Source”, “Cydia Installer”, “Dev-Team”, “”, “Saurik’s Source”,”ultrasn0w” and “ZodTTD’s Source”

      I’m not a genius when it comes to hacking phones, so I didn’t want to delete and risk ruining the unlock

      • Hi I have the same problem..iphone 3g 4.2.1 with baseband 6.15 and now I cannot make calls or send or receive texts. 3G and gprs internet is working fine.
        I’ve installed push doctor and this has not made any difference…help?

  • alexblabla

    I used to ave the some problem but then after like the 5 th time I jail broke it it came back and now my 3G 4.2.1 unlock works fine

  • Karl Haze

    Hi everyone,

    I need help, I bought an iphone 3gs 16gb off my friend, got it unlocked, but then stupidly (hindsight!) upgrade it to the new 4.2.1 firmware. The baseband is 05.15.04. And now I can’t use it to make calls or texts. Can I still unlock it?

    Thank you,


  • Juan

    Hi, is there any unlock for the iPhone 4 4.2.1??? Please help me with it.

  • ratz

    Hi, pls help me! im stuck wit iphone 3g baseband 5.14…so i jz want to know if i shud wait 4 dev-team 2 come up wit an unlock 4 it? r they working on it? wil they ever come up wit one in da future?…or else if ters absolutely no way, then i can go 4 da 6.15 baseband…cz it seems risky. some r facing gps n wifi problems…. pls advice me, thanx!

  • Hi, any update on Ultrasn0w for iPhone 4 4.2.1 with the new Base band??

  • rizky putra

    hi, how to unlock iphone baseband 03.10.01 iphone 4 ios 4.2.1… thx

    • wayner8088

      I don’t think there’s a jailbreak for iphone running 4.2.1 yet. The latest I believe is iOS 4.1 using iPad baseband 06.15. I’d go to to Dev-Team Blog to be sure!

    • eJaN

      There is no unlock tools yet for bb 3.0 yet. Wait for new unlock tools

      • wayner8088

        You can run the latest version of redsn0w and upgrade your baseband to the iPad’s 6.15, but doing so you’d void your warranty.

  • Carrie Carrigan

    it tells me that i have voicemails but wont dial out. I have the 3gs on 4.2.1 and downloaded ultrasnow from cydia after jailbreaking. Did i do everything right? Do I need to contact tmobile to have them add the data pkg?

  • anil


    I have IPhone 4g firmware 4.2.1 baseband 3.10.01

    please help me

    how to unlock

  • Badjam

    Can someone please please help. I jailbroke and unlocked my iphone 3G running 4.1. I ran fine on the IPAD OS. Through a dumb decision, I RESET my phone to erase all previous user settings,which put it into a coma displaying the apple logo. so i tries to restore using itunes, but that didn’t help. I tried re-installing the IPAD OS but nothing.
    Any ideas, or to I just chuck the phone?

  • carrizzle

    try doing the jailbreak process again starting with putting it into dfu mode. I thought mine was gone and it went into coma so i just started the process all over again. also after i jailbroke it and rewrote the 5.14 baseband i had to boot tethered….

    if this doesnt work, then you actually reset the phone i would just chuck it or try to sell it. once you rewrite certain basebands, there is NO GOING BACK.

  • carrizzle

    btw- i used redsnow

  • Martin WINLOW

    Would it not be helpful to explain to us newbies how the devil you know what ‘baseband’ you are on in the first place? There’s no setting on my iphone with that name. MW

    • Martin WINLOW

      Don’t bother – I found it on another site – on the iPhone settings it’s called Modem Firmware – why the hell call it baseband then??? As if all this gobble-de-gook wasn’t bad enough as it is!!

  • need3GSjailbreak

    What are “old bootroms/baseband/modem firmware”? Any of these: 04.26.08, 05.11.07, 05.12.01, or 05.13.04?

    I have iPhone 3GS, ver 4.0 (8A293), baseband/firmware 05.13.05, jailbroke/unlocked from How can I upgrade to 4.2.1 to preserve my baseband and unlock? Is Redsn0w an untethered jailbreak (don’t need laptop to reboot)?

    Confused by:
    * If you have an iPhone 3GS with an old bootrom and are already unlockable but want to update to 4.2.1, please wait for the Dev Team to release an “unofficial” bundle for you that will get you to 4.2.1 but preserves your baseband. —- is this in the new PwnageTool?
    * iPhone 3GS users with old bootroms who want to go to 4.2.1 should not use PwnageTool. You should update to stock 4.2.1 first, then use RedSn0w to update your baseband.

    • need3GSjailbreak

      correction, that’s baseband/firmware 05.13._04_

  • need3GSjailbreak

    correction, that’s baseband/firmware 05.13._04_

  • wayner8088

    As far as I know, you cannot jailbreak and unlock an iPhone 3GS (with old bootroms) unless you upgrade to 4.2.1 first THEN upgrade your baseband to the iPad’s 06.15.00 with the latest pwnagetool. But by doing so you void your warranty with apple, and, as in my case, can’t get the GPS or 3G network to function properly. It’s very frustrating and have to wait for the next solution to come out. There are various unconfirmed reports saying that you CAN downgrade your baseband from 06.15 to 05.14.x but that brings you back to square one.

    • need3GSjailbreak

      Thanks for the insight wayner8088 – much appreciated! Yeah, I was just reading about the ipad bb 06.15 breaking GPS functionality and I rely on that too much to loose also.

  • Akshay

    Hi, When is the unlock for Iphone 4, IOS 4.2.1 on baseband 05.10.01 is getting released? Please update if any one have any firm information. Thanks.

  • LeAnn

    I need some help. I updated my nephew’s 3G to 4.2.1. Jailbroke it using redsn0w. Then I followed the directions on how to upgrade the baseband so I could unlock it. It went through all the steps (I think)…I saw the walking pineapple on the screen and everything went through. However, the phone did not reboot all the way after this happened. It stuck on the silver apple. I tried booting tethered, but it gets stuck on the pineapple….I can’t restore in itunes, so I am assuming that the baseband upgrade went through but now I am at a loss. Does anyone have any ideas? itunes will recognize the phone in recovery mode but tinyumbrella 4.21.11 won’t. If I just made this thing into a paperweight he’s not gonna be too happy…..

    Oh, I didn’t have the ipad baseband firmware already on my computer. Would downloading it first be of any help? PLEASE SAVE ME!! Thanks so much!!

    • Yep

      Dude, you are so fu*ked, why experiment on next mans sh*t?!

      You need to connect the device to your computer, and repeat the steps to go into dfu mode, sleep button 10 secs and that, it’ll go into dfu mode, then just jailbreak again.

      OR just insure it and break it with a hammer.

  • vixell

    hello, i accidentally restored my iphone 3G 4.2.1 with baseband 06.15.00 and now i can’t get out of recovery mode. could someone help me with this problem. TIA

  • Kito

    brvao! my phone4 4.2 was successfully unlocked just in today..gonna have some party then…..

  • joel

    hi.. i need some advice… i upgrade my iphone from 4.0.1 to 4.1 with 05.14.02 bseband… i know that ultrasnow can’t unlock 05.14 BB and i have to upgrade the BB to 06.15… but i read some review that there are problem with 06.15.00 BB (GPS, wifi, etc..)
    so i need advice… what should i do… update the BB to 06.15.00 or just wait until the unlock for 05.14.02 released…

    • wayner8088

      My advice is to stay on 3.1.3 for as long as you can. I have a 3GS with 06.15 baseboard, and my GPS is dead and my 3G is about as fast as an Edge network.

  • henry

    I have IPhone 4g firmware 4.2.1 baseband 3.10.01

    please help me

    how to unlock

  • Arun

    I do not think the unlock for this software version for Iphone 4 is out yet. You need to wait until ultrasn0w is capable of unlocking ur software version.

  • Kito

    hi everyone, GEVEY SIM interposer can help yr phone 4.2 get unlocked, it’s now available everywhere and am using it now….let me know if your stone still can’t be unlocked.

  • somethingmonumental

    I have an iphone 3G, ios 3.3 baseband 5.15. I jailbroke the phone using spirit, then using cydia downloaded utlrasn0w 1.1. The phone rebooted and since then I haven’t been able to connect to my provider (O2) or have any 3G access… I wanted to unlock so I could use the phone in Holland with a pay as you go sim – I travel a lot between the two countries – what is my best course of action now. Thank you for your help…

    • toyboat

      Don’t think you can unlock with 5.15, need to upgrade to 6.15.

  • shahin hasan

    iphone ver; 4.2.1 unlock, How it possible. plz help me

  • Qassop

    Hey guys! I have 3g 4.1 base 6.15 unlocked but i cant connect to youtube at all! And multitasking is not working also!


  • Hey guys! I have 3g 4.1 base 6.15 unlocked but i cant connect to youtube at all! And multitasking is not working also!
    Itunes is failing! Cant back up my iphone3g


    • wayner8088

      Multitasking doesn’t work on 3G, only 3GS and 4. As for YouTube, you have install Push Doctor once you’ve jailbroken your phone through Cydia.

  • hey i want to unlock iphone 4 but i can’t 🙁
    can every one help me plzzz

  • iphone 3g, firmware 4.2.1, jailbreak using redsn0w, everything worked perfect until now. My apps and other programs get stuck and the OS restarts everytime. I am confused. Can you please advise?

  • Emad bin imran

    4.2.1 update problem what can i do

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