I went to prepaid.citi.com/uswindowsphone and registered my account. This info is from the Card Tips section:
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Making purchases: Choose "credit" (not debit) when checking out. (It doesn't make sense since you're using a debit card, but that's the way the processing network works.) Also, you don't need a PIN to complete purchases.
Avoiding "cash equivalent" transactions: Sorry, but you cannot use your card for cash equivalency transactions (e.g. ATMs, Western Union).
Spending up to your limit: Remember... your card does not offer you a line of credit. You can only spend up to your available balance.
Purchasing gasoline: For security reasons, your card will be declined if you try to purchase gas "at the pump." To complete your transaction, just ask the service station attendant to swipe your card.
Using your card at restaurants: Sounds crazy, but restaurants may temporarily "authorize" your card for 20% more than the purchase amount. They do this to cover gratuity. Make sure you have enough funds in your account to cover the authorized amount.
"Splitting" Payments: If your purchase amount is more than the amount available on your debit card, you can usually supplement with another form of payment (cash, check, or other card).
Make sure the merchant allows split payments
Use your debit card as the first form of payment (specifically tell the cashier the exact amount to deduct from your debit card)
Use a supplemental form of payment to cover the remaining purchase amount
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So it looks like you can use that $25 dollars at any place that accepts Visa. You just gotta make sure to use it as credit. I'm thinking I might purchase Navigon with my regular card and use that $25 for more Christmas gifts for the fam.