Jailbreaking friends phone Confused and have questions

[cnmsales]

First let me say I am nt a total newb to the technology world. I am an Android guy and have rooted plenty of those. My buddy has been given an iPhone and I believe it is an iPhone 3gs. Model# is A1303. Version shows as 4.2.1 8c148. He is on tmobile and this is an ATT phone.

So I am in need of some guidance on how to get this working on tmobile for him.

#1 Does the phone have to be jailbroken before it can be unlocked?

If so, can someone point me to a step by step guide to jailbrake it. If not can someone please show me a step by step guide on unlocking it.

I have tried using both blackra1n and redsnow. With BR it stated it was connecting to phone but nothing ever happened. Using red snow, I get the error that the device cant be automatically read or something to that affect.

Let me say thank you in advance for any help and guidance you can give.

 

[snowtrooper1966]

Yes, the iPhone must be jailbroken before it can be unlocked for use on tmobile.
Here is a step by step guide, walks you through most any phone iOS config:

http://www.iclarified.com/unlock/index.php

Have fun!

 

[cnmsales]

Snowtrooper, thanks for the fantastic link. When going through the guide it tells me

Important​

There is no unlock for your baseband yet. This phone is on 4.2.1 So can this phone not be JB? Or do I have to upgrade firmware first?​

 

[snowtrooper1966]

Sorry it was not that easy.....

Ideally, for ease of use, you would want to be on a firmware that supports jailbreakme.com
4.2.6 through 4.3.3, IIRC.
It's a method you use right on the device, super easy.
Since the device has not been JB'd before, not sure u can select specific firmware to update to. May have to go to 5.0, the last firmware Apple officially supported for the 3GS.
Since you need to unlock, there's also the modem firmware (baseband) to consider.
Go to settings>General>About and let us know what it is.
Lots of little nuances, and I may be off base a bit.
I'm sure our resident JB master, Europa will stop by. She's the best, and regularly patrols threads such as this....

 

[fijiman]

The important thing about software unlocking an iPhone is the Baseband value...this can be found in Setting>About>Modem Firmware...
If your lucky enough to be on a baseband that is unlockable it's easy to jailbreak iPhone and unlock...
Don't update firmware as this will update the baseband as well.
iPhone 3Gs users are lucky enough that they can, regardless of the baseband they're on, still UNLOCK their iPhone using an iPad Baseband fix this must be done with caution...
Or you can use an interposer sim like Gevey to give you the unlock...

 

[cnmsales]

Ok, at work right now. Will update the thread with the requested information as soon as I get home this eve. Thanks again for all your help. Its greatly appreciated.

 

[cnmsales]

Modem firmware shows as 5.15.04.

 

[snowtrooper1966]

Don't think 05.15.04 can be JB'd.
U may have to flash your device with the iPad firmware for redsn0w jailbreak.
Couple caveats. Some users who flash device with iPad baseband lose GPS functionality and have issues with WiFi.
I did not when I had to use iPad baseband for my 3GS.
Also need to check what botrom device has.
Old botrom will get untethered jailbreak, newer gets tethered.
video below details how to check.

Hopefully Europa will chime in.

Check out this YouTube video, walks u through it.