String literal. A string literal or anonymous string is a type of literal in programming for the representation of a string value within the source code of a computer program.
As usual, the devil is in the details. For instance, with some prepaid wireless plans, your minutes are only good for a limited time, usually 30 to 90 days. If you don't use them before they expire, they are simply subtracted from your account anyway.
Prepaid Cards. Prices on the AT&T wireless prepaid cards, which is a convenient way to refill your account, range from $20 to $100. These cards expire after 90 days. Unfortunately, you will struggle with finding the exact details of the cards on the official site. AT&T Customer Service