getting a sim card from overseas
For a number of reasons, I need to get a sim card before I land in USA next month. I noticed on the forum that there were some customers who got a prepaid line while overseas (for example https://forums.att.com/conversations/online-account-access/activate-a-sim-card-outside-the-us/5defd895bad5f2f6066d4f3d).
Can anyone inform me how to do this? AT&T does not sell sim cards in Singapore as far as I can tell.