If you run out of minute limits, you will not be able to call until your next subscription period. However, you still will receive incoming calls.
If you try to call, you will receive a notification that you are out of limit. On the relevant notification screen, you will also see the date of the next period.
In the future, you'll be able to buy additional minute packages to add more minutes to your main plan.
You need a stable internet connection for incoming SMS, the sending number must contain +1 country code and should be within US territory. We are not able to forward SMS if these conditions are not met.