Need help unlocking please. First time :)

[Chad711]

Hey my friend is coming over in a few and he has never updated his firmware since he bought the iphone. He is on tmobile. Pretty sure he has a 3G.

What firmware can I update him to and still unlock his phone?

How do I unlock it?

I've done jailbreaking on mine many times and have even restored to firmware that was backed up on Cydia so pretty savvy with understanding some things.

Thanks

[iYeow]

You can restore to 3.1.3 and jailbreak and unlock using this link here :
How to Jailbreak 3.1.3 iPhone 3G & iPod Touch 1G/2G Windows & OS X
Ultrasn0w to unlock from Cydia.
Opinion, you can jailbreak iOS 4.0 but it is very slow on multitask and lots of complain on 3G.

[Chad711]

Thank you. But os4 is not unlockable right?

Edit also I meant to ask does the sim card need to be in the phone when you unlock it to tmobile?

One other thing. I dont think his phone is jailbroken. can I still get it back to 3.1.3 if the firmware is not SHSH on cydia?

[iYeow]

You can downgrade to any version because 3G doesn't require shsh. However, you will still encounter 1015, you have to use quickpwn or irecovery or rslite to get out only then you are booted to emergency screen. Only when you downgrade you will encounter 1015, if you are upgrading this error will not come out.
Since 3G, is not jailbroken, depends what version you want. If you restore to 3.1.3, then use this link
How to Jailbreak 3.1.3 iPhone 3G & iPod Touch 1G/2G Windows & OS X
If you want to jailbreak at iOS 4.0, just restore to official 4.0 and run Redsn0w 0.9.5b5 to hacktivate, jailbreak and unlock with Ultrasn0w.

[Chad711]

We are going with 3.1.3.

I think I need to use Xp for irecovery as it hasn't worked for me in the past with windows7.