How to Prepare your iPhone 4.2.1 for Unlock using RedSn0w

By , Nov 29, 2010

We’ve seen yesterday that we the release of the updated UtraSn0w unlock, there are a few to be met to unlock iPhone 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.

But what happens if you’re not on one of those basebands? Depending on your phone model and configuration, you might have to update the baseband to 06.15.00, which is fully unlockable, then unlock using UltraSn0w.

In this tutorial, I will show you how to use RedSn0w to update your baseband to 06.15.00 so you can unlock your iPhone 3G/3GS 4.1.2…

Step 1: Before doing anything, make sure to read this. Seriously, read it over and over again. There is very important information in there that you must know before proceeding.

Step 2: Make sure you have the latest version of iTunes installed on your computer. If not, update iTunes.

Step 3: Make sure you have iOS 4.2.1 on your iPhone 3G or 3GS.

Step 4: Download RedSn0w 0.9.6 beta 5 as well as iOS 4.2.1 for your iPhone 3G or 3GS from our downloads section.

Step 5: Launch RedSn0w and browse for the iOS 4.2.1 firmware you downloaded in the previous step.

Step 6: Once the IPSW is identified, click Next. RedSn0w will start preparing the jailbreak data.

Step 7: Now make sure you select to “Install Cydia” and “Install iPad Baseband”. A warning will pop up. Again, make sure you read and understand the risks associated with this.

Step 8: Make sure your iPhone is turned off and plugged in your computer. If it’s not, plug it in, then turn it off. Click next, and be ready to get your iPhone in DFU mode.

Step 9: Hold the Home and Power button together for 10 seconds. Release the Power button while still holding the Home button for a few seconds. Then let RedSn0w run its magic.

Done, your iPhone is successfully running a jailbroken iOS 4.2.1, and we have updated the baseband to 06.15.00.

If your device is an iPhone 3GS with old bootrom, you won’t have any problem after that. If however it is a newer bootrom, you will notice that you iPhone shows the “connect to iTunes” logo every time you reboot it. It’s normal. While very inconvenient, it’s the way it is.

To go around that, launch RedSn0w, plug your iPhone in and select “just boot tethered” just like the image below. It will kick boot your iPhone.

How to Unlock Your 4.2.1 iPhone 3G or 3GS

Now that you’ve gone through these steps, you can easily download UltraSn0w from Cydia to unlock. Simply install it, reboot your iPhone, and you will be unlocked.

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  • SgtGoldy

    PLEASE HELP – BRICK iPHONE

    So lets say someone accedentally clicked RESTORE after jailbreaking and unlocking…. How would that person Get 4.2.1 back and re jailbreak and unlock?????????????

  • Len

    OK. I got the jailbreak done, and did the tethered reboot, but when I went to Cydia to get the UltraSn0w it is nowhere to be found. Can anyone help with this?

  • abhi

    hi i’ve just jailbreak my iphone 4 vth redsnow n installed cydia n how to unlock my phone vth 4.2.1 vth 03.10.01 baseband.thanks

  • Robneus

    Ok, guys. I had a lot of problems. The reboot loop was happening to me because I was using firmware for 3gs. I though my phone was 3gs, but it was 3g. So I install the official 4.2.1 update from apple trough iTunes. After that I followed used the same update file (iPhone1,2_4.2.1_8C148_Restore) with redsn0w_win_0.9.6b6 and selected only “Install Cydia” nothing else. Then after it finished, use the unlock tool and that’s it. It’s working fine now. I was a little scared to update it trough iTunes, but it went fine.

    • IpHoNe2345

      what was your baseband?

  • Ryan

    Thank you so so much, this worked, I can’t thank you enough, really, thank you! the tip of unplugging and re-pluggin when the white screen comes on works a treat! thanks dev team and evryone else for the info on this!

  • Iphone4gs

    I have an iphone 4gs (version 4.2.1) Do i hve to downgrade it to 3.1.3 to jailbreak it???? plz help me

  • Thomas

    Thank Very Much It Work Perfect!!!!!!!!!!!!!!!!

  • darsh

    Does it mean that 3GS with old bootroom on 5.12.01 will have to be necessarily be upgraded to 6.15. Cant we uncheck the option ‘use the ipad bb’ option and try with redsn0w. will query is what will be baseband after jailbreak? 5.12.01 or 6.15.

    Please help.

    Tons of thanks in advance

  • shom

    I got everything ok, But everytime my phone turns power off or goes dead (no battery) it will not get on again, unless I launch RedSn0w, plug the iPhone in and select “just boot tethered” to kick boot my iPhone 3gs.
    This is very annoying as it means I have to carry a computer with me.
    Anyone resolve this problem. tks

    • Sciencetor2

      Well currently your jailbreak is teathered, which by definition means you need your computer to boot up. If you own a mac you can download redsn0w 0.9.7b6 and use the “jailbreak monte” option only, which will unteather your device so that is boots normally, if however like me youre a windows guy, sorry but youre stuck until the dev team sees fit to port it to windows

    • Sciencetor2

      Well currently your jailbreak is teathered, which by definition means you need your computer to boot up. If you own a mac you can download redsn0w 0.9.7b6 and use the “jailbreak monte” option only, which will unteather your device so that is boots normally, if however like me youre a windows guy, sorry but youre stuck for now

    • Sciencetor2

      Well currently your jailbreak is teathered, which by definition means you need your computer to boot up. this isnt a glitch, its the way its made. If you own a mac you can download redsn0w 0.9.7b6 and use the “jailbreak monte” option only, which will unteather your device so that is boots normally, if however like me youre a windows guy, sorry but youre stuck for now

  • fadi

    Do I need a Sim Card for this to work. My sister gave me her iphone 3g and i want to use it as an ipod. I dont wanna do this until i know i DO or DONT need a simcard

    • Sciencetor2

      Sorry for the spam im writing from an ipod and it told me i wasnt posting, go figure

    • sciencetor2

      you shouldnt need one because its not a restore but if you want to use it as an ipod i would reccomend buying a phone book transfer sim card from radio shack, this wont give you service obviously but it will activate your phone for normal use and it is extremely cheap if you choose to restore or update

  • http://gmail.com harry

    hi , i have jail broken iphone 3G 4.2.1 with red snow , but i m not able to boot tether it , it stopped at a point ,[waiting for reboot] and now nothing is happening so , please help

  • veda

    process is freezing right at the “downloading jailbreak data..” screen…can any one help?iphone 3g on 4.2.1..

  • veda

    or it freezes at uploading “ramdisk” screen in pc..

  • Jabed Ahmed

    guys can any1 help me here..i downloaded the redsn0w nd the 4.2.1 firmware bt wen i run redsnow nd try to brows for the IPSW it doesnt finds it…it is on the desktop bt still it doesnt finds it….can some1 help me what to do here

    • Snos2

      Download the file again usinf firfox browser explorer does not dl in the correct format if you have dl it properly it should look alot like a lego brick icon on your desktop and not a folder full of files hope this helps

    • Snos2

      Download the file again usinf firfox browser explorer does not dl in the correct format if you have dl it properly it should look alot like a lego brick icon on your desktop and not a folder full of files hope this helps
      Snos2

  • WayneB

    Followed the guide for my 3GS, but Cydia doesn’t work when i clikc it, how can I unlock?

  • adam

    hi guy, i have the same problem, i just jb my 3gs and cydai was installed but it doesnt work. so i run redsn9w and just boot tether, first it seem to go well but it finish the reboot start, it struck and the screen appear the small banana and it stops there couldnt turn off

  • adam

    hi guy, now i cant reboot my ip and i can see there cyndia icon now but it doesnt work so my ip still locked. what should i do? anyone can help? please!

  • sathish

    Is it possible to unlock
    iphone 4
    modem firmware: 03.10.01
    version 4.2.1 (8c148)

  • bryant

    thank you so much for helping us.. you make it easier for us.. thanks again..

  • Dj Jazzy Death

    im just wondering, do i have to select “update to ipad bb” if i am on iphone 3g bb 5.11.07? Can’t i just keep my bb?

    • Snos2

      No do not update bb just jailbreak
      Use red snow and only tick install cydia

  • JiN

    What will I do with my 4.2.1 bb 03.10.01?
    I can’t even upgrade it to 06.15. No upgrade to iPad bb choice to check on redsn0w.

    • Snos2

      Your phone cannot be unlocked yet
      Your baseband is higher than the ipad baseband toul have to wait for unlock
      May be out soon

  • ARRIAZA

    PLEASE HELP…!!!!!! I HAVE NO PROBLEMS UPDATING BASEBAND 8GB 3G 4.2.1,,,,, BUT WHEN IT COMES TO UPDATING IPHONE 3gS 4.2.1 TO THE IPAD BASEBAND OR EVEN JUST JAILBREAKING IT, I ALWAYS GET STUCK ON waiting for reboot I CAN’T FIX THAT… AM AN UNLOCKERS AND I HAVE TRIED MANY WAYS FIX THIS BUT I CAN”T. I HAVE TRIED PULL OUT AND IN THE USB,… MANUALLY SHUT IT OFF AND ON… BUT NOTHING…USING DIFFERENT VERSIONS OF REDSNOW AND NOTHING… REBOOT MY COMPUTER AND NOTHING…. WHAT SHOULD I DO NEXT????

    • Snos2

      I had exact. Same problem i was usung 3gs fimware insted of 3g have same version number but are different
      Just check that also put device into dfu
      Then plug into itunes update your firmware to 4.1from file on your pc press shift and hold shift then click restore itunes will ask for file do this first then check the above hope this helps
      Thanks snos2

      • Ryan

        I have same problem. So just to clarify, restore on itunes to 4.1 or 4.2.1? Whichever i restore to, i will then need to choose that file when choosing the ispn for redn0w? Still need to update baseband to ipad? sorry for questions. thanks for your help, much appreciated.

      • Snos2

        What fone are you trying to jb and what firmware and baseband are you on

  • SaulSalsa

    I freaked out when I updated my 3G to 4.2.1 and couldn’t be unlocked, took the risk installing iPad’s baseband, worked just great. Got to love this blog.

  • iphone4

    Help me pls!! After i press install cydia it doesn’t reboot and only show a apple icon.HELP!!!im using a iPhone4 4.2.1

  • Ryan

    To Snos2, hopefully you can help! I have iphone 8gb 3g, not 3gs. Have installed cydia and ipad bb through redsn0w, worked a treat. However, my network is locked, says no service no matter what sim i put in, no service. My wifi will not find local wifi spots, it doesnt seem to be working. so when i load cydia, says unable to connect, so i cant install ultrans0w to unlock. Any suggestions??
    Thank you!

    • Snos2

      The only way is to find internet for your fone . So it can download , once in cydia goto manage sources ultrasnow
      And install the latest wich i think is the 1.2
      Hope this helps

      • Ryan

        Thats the problem! with no service on network and wifi not working, can’t get internet on phone, so cant download ultrasnow on cydia! Damn it! Thanks for your help!

  • Rafael

    tengo un iphone 4 IOS 4.0 baseband 1.59,, estaba desbloquea y con JB, cometi el error de restaurar contenidos desde el iphone y se quedo en la manzanita, nunca se guardaron shsh, por lo que no se que hacer, si lo restauro a la 4.2.1 que es mi unica opcion por lo de las firmas, tambien actualizará la baseband, alquien que me ayude?

    I have a 4.0 baseband iphone 4 IOS 1.59, was unlocked and JB, I made the mistake of restoring contents from the iphone and stayed in the apple, never kept SHSH, so you do not know what to do, if restored to 4.2.1 which is my only option at the firms, also update the baseband, someone help me?

    • Snos2

      The only thing you can do is stay on 4.2.1 wich can be jb but as yet cannot be unlockedyou will have to wait .
      Hopefully not long

  • bazman

    i now have an at&t Iphone 4 -4.2.1 03.10.01 can it be unlocked?

  • veda

    my iPhone 3g 4.2.1 stuck on connect to itunes while jailbreaking. can anyone help me???

  • http://jamajama.com colas

    daghan nata! samot ang akoa naguba na

  • http://jamajama.com colas

    ok na.. salamat! thanks

  • http://jamajama.com colas

    just read carefully the instruction and understand it.. and you will get your ios 4.2.1 jailbreak… thanks a lot…

  • snowii

    Morning….. HELP! I went through the process as above and everything went fine…. but my iphone 3gs wouldn’t open cydia or safari…. so I stupidly tried to recover it in itunes ending up with an error code (1015)…. now it won’t come out of recovery mode (I have tried using tinyumbrella) HHEEELLLPPPP! (please) :(

  • saad

    PLEASE I NEEED SOME SERIOUS HELP I HAVE AN IPHONE 4 FROM AT&T and ITS VERSION IS 4.2.1 with baseband 3.10.01. CAN IT BE UNLOCKED? if not then how long will it take before it can be unlocked. NEED SERIOUS HELP FROM ALL YOU OUT THERE. THANKS.
    WAITING….

    • Snos2

      It cant be unlocked at least for now

      • Saad

        @Snos2 thanksss for helping. So do you know that how long it is going to take to UNLOCK this iPhone version? And what should I do? HELP PLEAsSSsE. Thanks.
        Waiting,…

    • George Mack

      I have the same prob,,, iphone4 on 4.1,,, n I’ve been waiting 4an unlock 4 years it feels like,,, still no luck in unlocking my ip4,,,, still waiting n still seeking help

  • snowii

    iphone 3gs 4.2.1 baseband 06.15.00 downgrade and unlock!

    I found a solution…. by accident! (for mac osx) As I said above my iphone 3gs on 4.2.1 with baseband 06.15.00 I got stuck in a loop after performing the above method (using redsn0w to update the baseband – old bootroom) and then trying to sync with itunes – stupid i know but Cydia and safari were not working and I’m quite new to this…. It was stuck on an endless loop between the apple screen and the connect to itunes screen. I could not get it into dfu mode or find the correct info…. Eventually I managed to get the 3gs in dfu mode…(for those who are as new to this as me – hold both buttons for ten seconds or so and then release the top button when the screen goes black – you can see that it is still on around the edges if you look carefully. You MUST do this whilst the iphone is connected but not with itunes running!) I then fired up redsn0w and used the 4.2.1 ipsw file…. then select pwned DFU mode and let redsn0w work its magic…. redsn0w will then tell you that it is done but the screen will still be black. Fire up itunes (my mac came up with 2 iphones- just eject one) and then it’s time to restore (making sure that you hold down the alt/option key on your mac as you click restore) You must then select and use the 4.0 ipws file (download this before starting and put it on your desktop) itunes will run its restore but then come up with an error code 1015….DON’T PANIC! What you must then do is disconnect your iphone, then close itunes and then put it in dfu mode again. Your iphone will show the same ‘connect to itunes’ screen – ignore this. Download and then fire up Tinyumbrella. Use it to disconnect…. your iphone will show the same screen as it does when updating with itunes… and then…. Magic…. It will work! Connect the iphone to itunes to activate it! It will now be on 4.0 with the ipad baseband. The next step is to connect your iphone to the net (using wifi) and then go to jailbreakme.com to jailbreak your iphone. Then just run cydia and ultrasn0w and bingo… downgraded, fixed unlocked! Sweet! Hope this helps some people as it took me ages to figure out!!!!! :)

  • snowii

    oh… i forgot to mention that I had no blobs and the ripsaw files were not modified! :)

  • snowii

    ipsw files!

  • WayneB

    hi Snowii, didn’t work for me Itunes just says it’s still in recovery mode and no matter how many times i disconnect it with tinyumbrella, it just goes back into tinues saying it needs to be restored and it’s in recovery mode.?

    • Snowii

      Are you using the most up to date version of iTunes? Also which iPhone do you have? Make sure when you disconnect the iPhone from iTunes after the restore you don’t push eject… And that iTunes is shut down before you run tinyumbrella! Hope this helps! :)

  • Gan

    hello there is it possible to jailbreak iphone 4 with os 4.1

  • WayneB

    Hi Snowii, Using Itunes 10, downloaded lastest one today, Iphone 3GS, but i beleive it has new bootrom. Thanks

  • WayneB

    I get a 3194 error in itunes when trying to restore the 4.0 firmware

  • Thierry

    I have a 3G which I updated to 4.1 with the 5.14.02 baseband…I have tried to unlock it with Snowbreeze 2.1 but no luck!
    When trying to restore with the custom firmware, itunes is giving me an error code…Anybody tried that?
    I’ve tried to use Ired to bypass itunes errors but no luck either!
    Should I update to 4.2.1?

  • Thierry

    Any chance of getting Cydia without jailbreaking your iphone?
    meaning from the web since I have wifi…

  • Kirsten

    I did this process for my 3gs and cydia will not open… any ideas on what might have went wrong? Should I repeat the whole process?

  • John

    I’m one in a long line of 3GS owners who followed the instructions carefully. Cydia appears (but blank, no logo) and won’t open! Please, please, answer the questions from (now) 4 of us – what to do next? Can we put cydia on it another way? Do we go back through Redsnow b6?

    Any ideas?? Thanks

    • Snos2

      Look have you read the instructions properly ? After jb cydia will show blank until plug phone into pc
      Turn off
      Re run jb
      And tick box just boot tethered now
      And like magic when phone is on cydia is there .. Ta,daa
      Or you could go the easy option and download greenpoison wich is now available for pc and its untethered
      Hope this helps snos2

  • Andrew

    Followed instructions above and all seems correct while using redsnow. It says its done and to rerun redsnow and choose “Just boot tethered right now”. However, when i do this it tells me to put device in DFU mode (so i do) and it completes the process but will not boot. Its stuck at the “connect to itunes screen”. Any help is GREATLY appreciated.

    • Andrew

      well, i installed cydia again through redsnow and it finally booted up! However, (lol) I have no wi fi capabilities, therefore, unable to open cydia. going on three hours of this :(

  • Andrew

    Also, it is cycling between the apple logo and “connect to itunes” screen apprx every minute.

    • Snos2

      Look whyuse a tethered jb when there is a untethered ? Update via itunes it will fail . Then jb with green poison
      http://www.Greenpois0n.com
      Thanks snos2

    • Andrew

      Okay, so hopefully this helps someone with the same problem I encountered (see above). In order to correct my wi fi problem, I simply ran through the baseband upgrade again (this time redsnow took longer to flash baseband)! Finally! My wi fi worked and i was able to open cydia and download ultrasnow to unlock, rebooted iphone and popped a Tmobile sim card in and made a phone call!!! Now, I read all night my 3gs NEW bootrom was going to be tethered after the bb upgrade but NOPE! I restarted the device multiple times and it works perfect without connection to a PC. Basically, if it doesnt work the first time try it again! and again! This crap is very temperamental!

  • bcx

    please unlockd baseband 5.14.04 on ios 4.2.1

    iphone 3gs

    the risk to upgrade the baseband to 6.15 its not for

    i would be forever grateful jeje

  • SaL

    Hi. I am completely new to this and am really fazed by all this jargon and feel very confused and lost. I have iphone 3gs, ios 4.2.1, and baseband 05.15.04 …. I need to unlock the iphone, where do I start??? Can someone please give me clear short instructions without making it too complicated please??

  • Mackman4.1

    I hav an iph4 running 4.1 sw,, (jail-broken) I can’t seem to unlock it’s carrier…. I’ve been waiting, Can any1help,,,I gladly appreciate it thanks

  • aary

    my baseband is 05.13.04 and i try with RedSn0w 0.9.6 RC8 and it stuck with dowloading jailbreak page can someone help me how to fix that. that

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