[Cali]

Hi all,
M friend wants an iphone but doesn't want to transfer her service yet.
My iPhone is jailbroken etc, but I also have att service.
Can I jailbreak her iPhone in a windows pc so that she can use all the other functions of the iPhone.....ipod,internet etc?
What is the best method if she gets 1.1.2?

Thank you,
Cali