Unlock iphone 4 with ios 6 for t mobile?

I have a at&t iphone 4 with ios 6 (10A403) and firmware 04.12.02. I had it jail broken but then just set it aside and kinda forgot about it and was wondering if there's any way to unlock it so i could use it for t mobile?

Only att can unlock it.

Hi, You can unlock an AT&T network locked iPhone 4 Safer and easier using remote unblocking service. This method of unlocking is very safe, simple, affordable and quick. You can get the remote unlocking service for an iPhone 4 from http://www.simpleunlocking.com/apple-iphone-4/rs16wp9/ at affordable cost. For further assistance you can visit http://www.mobileunlockguide.com/apple-iphone-4 This site provides free step by step unlocking instructions. This could help you understand remote unlocking service better. Once you have unlocked your iPhone you can use it with T-Mobile or any other GSM network. All the best mate.

A great service I have used is iphoneunlockedcheap.com they did it in less than a day. If the iPhone is yours and you are out of contract and you are the original owner, contact AT&T they may do it for free. But if you don't want to wait try an online provider. They do work