How to unlock a Iphone 4 for T-mobile?

I want to get an iphone, however i have t-mobile so in order to get an iphone i need to get one from AT&T and unlock it. How do i unlock it? Is it different from the iphone 3?~ My sister unlocked her Iphone 3G just by calling AT&T giving them a number and then done! Easy, is it the same way for the 4? Please help with MY question. No need to add all the reasons why i should't.

I think the same process should work the same for the iphone 4 so you shouldn't have any problems.

You can buy iPhone 4 from AT&T and Unlock it. The AT&T will unlock your iPhone 4 only when your contract is over or you can pay a large amount to AT&T to unlock. To easily unlock your iPhone 4, you can use Remote Unlock Service provided by http://www.unlock-zone.com/apple-iphone-4/rs16wp9/ .It is safe and easy. They will remotely unlock your iPhone 4 after getting information of your Country and Current Network in use.

There are many services out there that will factory unlock an ATT iPhone for cheap. One I used is iPhoneUnlockedCheap.com They do not jailbreak it (which is very risky). I recommend you check it out