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I know this is a pretty silly question to ask, but I am not really experienced with JB-ing yet. My question is, what exactly is an iPhone's baseband and what some basic info I should know about it so I don't mess up my phone? Also, if I don't unlock my phone, will I have to worry about messing something up with my baseband? One last question, what does it mean to "preserve a baseband" and "upgrade/downgrade/change a baseband" etc. (I've read a lot about it in the FAQ and don't really understand what it means)?

Thanks in advance

asked 20 Mar '13, 20:24

pzp1997's gravatar image


closed 31 Aug '14, 16:45

theiphoneguy's gravatar image

theiphoneguy ♦

The question has been closed for being "Solved" by theiphoneguy, 31 Aug '14, 16:45

I gather from your other question that you are using an iPhone 4, so you really don't need to worry about it. If you're on iOS 6, your baseband isn't software unlockable, and basebands on any device other than iPhone 3G/3GS cannot be downgraded.

In short, the baseband is the part of the iPhone that makes it a phone and not an iPod. It's the firmware that talks to the cellular radio hardware.


answered 20 Mar '13, 20:44

spockers's gravatar image

spockers ♦♦

Ok. Your baseband is what controlls all your cellular stuff.

To use a sim card other than the one the company gives you (most of the time), you need to unlock the phone to use another sim card. To unlock the phone, you need to "hack" the baseband to allow this unofficially. Some versions of basebands are not "hackable", so you need to preserve the baseband so you can continue using your unlocked phone. Sometimes if u upgrade your baseband by accident, you need to downgrade it to be able to use your phone unlocked.

My advice is if you are not unlocking your phone, do not mess around with the baseband because doing this can really mess things up. As long as you don't try to change your baseband, and you don't need a software unlock, I would not even touch the baseband :)


answered 20 Mar '13, 20:33

jailbreakhelp313's gravatar image


One of the steps to downgrade an iPhone 4 from iOS 6.1.3 back to 6.1.2 says:

"If your device is an iPhone, first create a NO_BB ("no baseband") custom IPSW using redsn0w and then follow the rest of these steps. (To do this, open redsn0w, click "Extras", click "Custom IPSW", and give it a normal IPSW for your device.) If your device is an iPad or iPod touch, ignore this step."

Anyway, you're saying owners of iPhone 4 don't need to worry about baseband at all. Right?

Does that mean i don't need to create a NO_BB custom IPSW and ignore that step? Also, does that mean i can just use the standard IPSW i downloaded from Apple as base to stitch my SHSH blobs?

(Btw, i can use whatever sim i want on my iPhone 4, so i guess that means it isn't factory locked)


answered 21 Mar '13, 08:49

effective's gravatar image


@effective read the above comments once again and you will understand.

(21 Mar '13, 09:38) sandkuma002 sandkuma002's gravatar image

@sandkuma002 what i understand is that my assumptions seem correct, as spockers says you don't need to worry about baseband on an iPhone 4

i guess the logical conclusion is that i CAN use the standard IPSW from Apple and stitch my SHSH blobs directly to it

but i'm not an expert (actually i only own an iPhone since couple of weeks and jailbroke it only few days ago…) and i'd like to be 100% sure of what i'm going to do to avoid messing up with a 400 euros piece of technology, you know…

(21 Mar '13, 09:53) effective effective's gravatar image

Ok @effective, here is the thing- if you were on baseband 1.59.00 on your iphone 4 and your phone was carrier sim lock and you had unlocked it with ultrasn0w, you will have to preserve baseband otherwise you will loose unlock. Also if you can use any sim from any carrier it is called factory unlock and then you need not preserve baseband. Also if you are using Gevey sim for unlocking your iPhone 4, it is better to preserve baseband because newer baseband are not unlockable by all Gevey. So even in iPhone 4 baseband preservations can be necessary. And @spockers was perfectly right because he was specially talking about OP question only.


answered 21 Mar '13, 10:08

sandkuma002's gravatar image


now that's what i call clarity! much appreciated, thank you @sandkuma002

i'm about to proceed my downgrade, wish me luck ;)

(21 Mar '13, 15:34) effective effective's gravatar image

@effective, redsn0w cannot create custom firmware for ios 6.1.2. You will have to use sn0wbreeze in ifaith mode to stitch blobs.

(21 Mar '13, 15:39) sandkuma002 sandkuma002's gravatar image

yeah, i'm aware of it and that's exactly what i'm doing, thanks!

(21 Mar '13, 15:43) effective effective's gravatar image

Please share your experience after custom restoring in itunes, I have just put a question that many jailbreakers are stuck at black screen after reboot!

(21 Mar '13, 15:52) sandkuma002 sandkuma002's gravatar image

holy sh** i made an error during the procedure

'Open iTunes and hold down the "Shift" key (on Windows) or "Option" key (on Mac) and click on Restore.'

instead of holding down option key and click on restore, i held it down while opening itunes… fu**

then i went into the restore process, but unsuccessfully as i got an error msg (it was so quick – and i was so shocked - that i didn't write down the error number)

so now i'm stuck on black screen… not sure if i can say i'm stuck on Pwned DFU or what…

any suggestion on what to do now?

(21 Mar '13, 16:18) effective effective's gravatar image

Use iReb/redsn0w to put is again in pwned DFU and try again with itunes!

(21 Mar '13, 16:22) sandkuma002 sandkuma002's gravatar image

i'm still getting the same error (1601) again and again…

i checked it out on the apple website and they say it may be related to the usb cable or bad internet connection… which is strange

i'll try again till i run out of patience

anyway, say i won't be able to complete the process, it looks like i can't boot my iphone anyomre… it's stuck on black screen, what should i do?

(21 Mar '13, 18:08) effective effective's gravatar image

i'm done with this for today (also because of that black screen problem you mentioned – will definitely follow that thread)

my iphone is running again (i guess i just made a mistake entering the dfu mode and did an hard restart instead)

just to share my previous problem: i was getting the same error message (1601) after the 'preparing iphone to restore' phase whether i held the option button (and selecting my IPSW) or not (letting itunes take care of everything)

don't obviously know what that may mean… :(

(21 Mar '13, 18:57) effective effective's gravatar image

please i want to chat online with someone who had experience and he know to help me in this stuff

i have my iphone 4 its type is : iPhone 4[GSM] [iPhone3,1] its was stuck in the activation screen i solved that problem and i downloaded ios5.1.1 and downgraded my device to this ios but now i have problem with the baseband it is stuck on NO SERVICE and i put sim inside it and no signal no carrier please if someone know how to help me in this steps just contact me in my E-mail: email removed

and please i need that help to fix that problem waiting someone is experienced to help me about this issue

Thanks all


answered 31 Aug '14, 16:16

sliso24's gravatar image


edited 31 Aug '14, 16:43

theiphoneguy's gravatar image

theiphoneguy ♦

  1. We dont do email or offline support.
    2. Don't bump up old threads from one and a half years ago
(31 Aug '14, 16:44) theiphoneguy ♦ theiphoneguy's gravatar image

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Asked: 20 Mar '13, 20:24

Seen: 51,356 times

Last updated: 31 Aug '14, 16:45

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