Originally Posted by weekilter

With T-Mobile PAYG if you initially buy a $100 voucher it will last a full 365 days. After your initial $100 a $10 voucher is all that is necessary to renew for another 365 days. Buy an extra $10 voucher when you're in the states and you'll always be able to have a working account. I believe you cannot buy time with a non-US credit card though the easiest thing to do is to get a voucher or vouchers in the states when you're here. Just note that $10 will fulfill your obligation, but for the best per minute rate you need to fill with either a $50 or $100 voucher. You can also get voucher PINs through places such as callingmart.