What carriers can the iphone 3gs be flashed to?
I have recently purchased an iphone 3gs and i would love to be able to unlock it and somehow use it on a pay as you go plan?
 my first thought was to unlock the iphone and use it for virgin moble because there plans are the cheapest, but then i figured out that virgin mobile phones don't have sim cards… 
 If i got a at&t pay as you go phone, and stick that sim card into the iphone would it work?
 are there any other carries that would work?