Hmmm. I used a pay as you go card on my iPhone for a year. I live near NYC and visit there frequently. I did have data.
Originally Posted by wvy
However, my card was purchased direct from AT&T, specifically for the iPhone, and included a data plan.
To protect themselves from unrecoverable international toll charges, AT&T restricts, by default, international calling. You have to call customer service to enalble it.
While the value is associated with the SIM, it is really stored in the network. I have no reason to believe that it would go away but I used mine too fast to know with confidence.
About the worst thing that can happen to you is that you have to go into an AT&T Store. There are dozens in the City but there are also many franchise stores who cannot help you. Not like Brussels where one can buy SIMs at the kiosk.
Hope this is helpful.