Interesting. I found that the Att sim card I purchased a few years back was difficult to keep alive during my sojourns outside of the USA. In fact, after three months away this time I cannot even use it until I go into an ATT shop which is very inconvenient.
I just purchased the hotspot with sim card from ROAM and I hope it's going to be a good alternative. I'll let you know if I find it painfully slow.
Lorna