Im going to try something new and put together a few tutorials because like most Nerds I love modding and am keen to overcome certain lockouts in order to achieve a device's full potential.
Note: I am not an advocator for piracy so and do not condone the use of modifications for piracy in general.
Note: (2) Disclaimer, i am in no way shape or form responsible for any individual or third parties bricking their phone so please do not attempt to lay any blame on myself or Nerdgenious.com, Kindest Regards and happy Modding.
So let's get started....
You need an Iphone 3GS, it doesn't matter what firmware or baseband (mobile firmware) that you have it on as this guide works with all 3G'S on all basebands.
Firstly if you do not have it install Itunes.
Now you need to go to an Iphone modification site and Download the firmware of your choice, for the device that i have been working on I decided to download firmware 5.0.1 from Iclarified, now set the Phone to DFU mode, this can be done by holding down the on/off switch for 9 seconds then by keeping your finger firmly pressed hold down the center button for 9 seconds, and finally after taking your finger off the on/off switch whilst still holding your centre button check to see if your phone has gone blank, if done right you should see windows installing a new driver for your iphone.
Now open Itunes, it should detect your Iphone 3GS in dfu mode, it will ask you to restore your phone so now press shift and select the 5.0.1 that you have downloaded from Iclarified.
Itunes should now install the new firmware without any problems....
Once the new firmware has been installed you need to download and Open the latest redsnow from Iclarified.
Open redsnow and click on jailbreak, it will ask you to place your phone back to DFU mode, follow the instructions above or watch the tutorial video if you have any issue's in doing so, redsnow should now show another menu and give you a list of options, make sure that you select the install cydia menu only.
Once this has been done you can now move to step 3
Open up cydia and click on the user settings, cydia should now be installing the relevant sources for basic use, exit cydia and close down your iphone.
You will now need to download and install Tiny Umbrella, once this has been done click on tiny umbrella and start it turning your phone on once again, after tiny umbrella recognizes your 3gs click save shsh, tiny umbrella will now download your .shsh blobs from your phone, this can be used to downgrade your phone to 4.1, now download the 4.1 firmware from Iclarified and place your phone back in dfu mode.
Once 4.1 is downloaded you will need to go back to Tiny umbrella and click on start tss server, open itunes and hold shift whilst clicking restore, select the 4.1 firmware and allow Itunes to downgrade your phone, once the process has finished itunes will come up with an error, don't worry it just means that you have sucessfully downgraded your phone, now click on tiny umbrella and unselect the start tss server, go to the exit recovery button and your phone should now be booting.
Once your 3gs has booted follow step 2 again to jailbreak your phone.
Once your 4.1 Iphone has now been jailbroken we need to now need to unlock it, in order to do this you will need to replace the 3gs's baseband with a moded Ipad one, this baseband is 16.5.00.
In order to do this you need to go back to redsnow, open it and click on jailbreak once again, follow step 2 to place your phone back to DFU mode, select the extras menu and tick place phone in pwned DFU mode (important: this needs to be done prior to installing your new baseband so don't skip this).
Once this has been completed go back into redsnow and select jailbreak, untick everything else and make sure only Ipad baseband menu is selected, your phone should now be going through the modification process, let it happen and if it fails a message that says ERROR will come up, just follow step four once again and it will eventually flash the baseband.
Once your new baseband has successfully been flashed turn your phone on, once booted check about, settings and it should say 16.5.00 under mobile firmware, go to cydia and install utrasnow, once ultrasnow has been installed go back to your settings menu, click network and turn 3g off.
insert your desired network chip and you should now have a jailbroken unlocked Iphone 3gs.
I was initially told that you could not update your iphone via Itunes after the new baseband install, well that my friends is aload of bull so im going to show you how to do that.
Firstly you will need
ireb revision 4 in order to place your phone into a factory DFU mode, this will allow you to install the firmware of your choice and allow Itunes to pick up your moded 3GS.
Open Ireb and select 3gs, it will ask you to place your Iphone into DFU mode, you can do so by following step 2, now select recovery mode loop fixer and it should boot your phone once again, go back into ireb and select 3gs once again, then select pwned DFU mode, it will now place your phone back to factory DFU mode and your screen should turn white.
Open up Itunes and hold down shift and restore, select firmware 5.0.1 and allow Itunes to install the firmware once again, once this has been done you will need to go through steps 2 and 4 in order to jailbreak and reinstall your baseband to fix your no sim error, once this has been done make sure that 3g is off, reinstall ultrasnow and you now have sucessfully installed firmwa 5.0.1 on an unlocked, jailbroken Iphone 3gs.
Thats it from me and happy Modding