Suggestions for iPhone 3G unlock?

[mrfriednoodles]

Device: iPhone 3G
Firmware: 3.1.2
Baseband/Model firmware: 05.11.07
Carrier : T-Mobile sim card
Jailbroken/Unlocked : Both done through blackra1n

Hello! I am wondering how I should update my already jailbroken and unlocked iphone.
I would like suggestions and help on getting to the most recent firmware possible for my phone.
Is it possible for my phone to reach 4.2 iOS?
And if it is, will my phone still remain unlocked or will I have to unlock again?
Lastly, if I do have to unlock again, is there any released method of doing so?

Thanks for the help

[i.Annie]

It's possible to get to 4.2.1 but it isn't recommended for that phone. Slows it down pretty badly, performs ok without multitasking and wallpaper but 3.1.3 is best for your phone.

If you would like to continue to do the upgrade, you can create a custom firmware with sn0wbreeze from ih8sn0w.com

Sn0wbreeze doesn't play well with the iPhone 3G so don't be surprised if it fails to work right or at all. Persistence though can sometimes help.

So long as you set into pwned DFU mode with redsn0w 0.9.6rc8 first (don't try to jb with it, only use redsn0w for pwned DFU mode), it will bypass any error during a restore to a custom firmware.

It would help if you have a Mac to use pwnagetool to create the custom fw instead of sn0wbreeze, but if you don't have a Mac and sn0wbreeze isn't working for you, find a custom 4.2.1 fw via Google that was created by pwnagetool. Just be sure the iPad baseband is *not* included or you'll screw up your GPS by updating the baseband.

Edit: and yes you'll lose the unlock but with a custom firmware to preserve the baseband, you can unlock again just by going to Cydia and installing ultrasn0w.