In need of expert help from you forum gurus

[Brownxx51]

Hello everyone. I got my hands on a iPhone 3GS unlocked jailbroken on 4.2.1 firmware on T-mobile. The modem firmware (baseband right?) is 06.15.00
My question is what is the latest untethered hacked firmware available now that I could still use to unlock my phone for T-mobile's service? And how would I go about updating my iPhone in a proper manner so I could jailbreak and unlock it again in the correct way? And my last question is what are the new features of the newest firmware that is out?

If anyone could help me answer these questions I would greatly appreciate it! There was a time ago when I had kept up with what I had to do to properly hack everything the right way, but its been a while and instead of just browsing youtube videos and get lucky I thought I post on these forums and see if any of you souls could help me out. Thank!

[n1ckn4m3]

You can upgrade to iOS 5.0.1 on your device. Use redsn0w 0.9.10b5 to make a No_BB firmware, then use redsn0w to put your phone into Pwned DFU mode and shift-restore the no_BB firmware. Then, use redsn0w to re-install the iPad baseband and if needed, use redsn0w again to complete the jailbreak. Once that is done, install ultrasn0w and you should be fine.

If you want legit push certificates, after everything above, download SAM (subscriber artificial module) tell it to revert lockdownd to stock, then tell it to deactivate the iPhone. Reboot the iPhone and plug into iTunes, this should re-activate the phone and generate unique push certificates. Download iPusher (free from App Store) to test push notifications. Once this works you can activate Facetime and iMessage so long as your phone allows for international SMS (a few will be sent to a UK number to activate Facetime/iMessage on your phone number and not just via your Apple ID)

When that's done, you'll need to configure the APN settings and if you want MMS, you'll need to edit one of the .plist files or else you'll just get the 'size restriction' error. All of this can be found by searching through the forums so I won't provide step by step instructions here.