I purchased a prepay sim while visiting NZ last month. I have now returned to Costa Rica where roaming is not possible. But I travel to the US frequently and would like to active roaming while there. While in Costa Rica my number will not be active for a few months. My question: how long will my number stay valid if I don’t use it for a while. And secondly, if I can use it in the US, what is the simplest way to activate a data plan for roaming?