@rahasya, I spent an hour with the ATT and also visited Apple store. The guy @ apple store clearly told me that i need the original sim that came with the iphone 4s that i have with so it's a no-go there. Tried with ITunes and it wont work unless I insert a sim and once I insert sim card and try to do with the itunes - it will bring up an activation screen with the phone number (that was tied up with the iphone) and is asking me the billing zip code and last 4 digits of SSN (which I believe is of the person that bought the IPhone 4S originally).