I am not sure how much goes on in the modem hardware and driver, vs what is going on in the sim card. If the sim card is used only for connecting to a signal from a given ISP, I would think (hope) I could buy a new sim in the U.S. for operation there.

Can anybody verify with actual experience one way or the other?

Thank you.

I took my AIS 3g aircard to Australia and it worked with one company straight away, then I tried another company and had to make a slight adjustment with the new company's help (on phone--but one person was not smart and then I called back later refusing to believe there was no option, and I got the smarter person--so don't give up). I have also tried it with TRUE, iMobile and DTAC here in Thailand and all work. So even tho I am American I have never tried it there AND America can be weird like that and too controlling but give it a shot. Maybe a friend in USA can walk in and ask at some business.