How to Unlock Sim Unlock iPhone 3G on Baseband 05.11.07 (upgrading to new OS)

[arhafiz]

Dear Friends,

I have an iPhone 3G 8GB. I got this on a contract 2 years back, but its on a contract. Its currently unlocked, so i can use any sim i like.


1. Whats the difference between sim unlock/unlock and jailbreak?
2. My phone is currently unlock by some shop guy, can i upgrade to OS 4.2 or do i need to take some steps ?
3. I have contacts on this phone which i have backed-up via iTunes and i usually downloads apps to my iPhone as well. Will these go lost after i upgrade and unlock? and will i be able to restore my back up after sim unlock?

I just want to know that if there is a detailed guide to help me sim unlock this.
I have version 3.1.2 (7D11) and Baseband 05.11.07, i want to upgrade my phone to the latest possible OS which has been tried and tested with sim unlock.

Please if anyone can guide me how to upgrade my this currently unlocked iphone.

Just post the guide link and i will read myself.

Thanks in advance,
Regards.