Hi all,
I am a new member here. I am using the Iphone 3G version 2.1 with a turbo sim card to keep my T-Mobile carrier.

I started reading some forums about unlocking the iphone 3G but it seems that there were issues after that.

Now, I am back to see whether there is any new software for unlocking it.
[1] Can someone direct me how to unlock it? maybe to the latest iphone version 3.1?
[2] How can I restore to version 2.1 in case there is any issue after unlocking?
[3] Can I still download applications from Apple Apps store after unlocking?
[4] Beside, what does the Jailbreak and Cydia really doing beside installing 3rd party applicatons other than from Apple?

Any inputs are much appreciated. Thank you. Ken