Can a Indian Mobile phone workable in US?

Short answer: yes, the phone will work Long answer: if you bought the phone in India and have Indian service then when you bring it to the States it will be international service and charge extremely. So while it will work you need to change your service and get American service. Then there will be no more problems that I know of. If you do have problems I would bring it to an AT&T store or an Apple store and get them to update it. This update will have any local (American) specific software needs. Enjoy the greatest phone ever made!!