Question about Giving old iPhone to friend on different carrier

[Shavo]

I preordered an iPhone 4 this morning and once I receive it I intend on giving my old iPhone 3G to one of my friends. I'm curious if there will be any issue with this since I'm on AT&T and she's on T-Mobile. I am aware she'll have to add a data plan to her account but I'm wondering if there's anything in my phone's firmware or otherwise that would prevent it from running through a different carrier once she inserts her sim card. Would it need to be jailbroken to work? Would there be any other steps to get it working on T-Mobile?

 

[lungho]

The short of this is that the phone would need to be jailbroken and then unlocked. There are a bazillion threads on how to do this in the Jailbreak forum. Also, iPhones on Tmobile will only have Edge connectivity and no 3G.