Originally Posted by Dave_S
but in reality the carrier has no real way to prevent an Android phone from doing that.
Are you sure about that. They should be able to see that you use the connection as a hot spot and just disble the data.
I wondered a bit about that because if you as a tourist buy this T-mobile sim card for $50 I think the contract says that you are not allowed to use it as a hot spot but of course it works to do it at least if you have an European phone.