You haven't won anything. If you ask, the telemarketer must tell you how to participate without buying something or paying anything. A telemarketer who offers to sell goods or services in connection with a prize promotion must give the sales pitch before the prize description. The telemarketer is breaking the law. The Telemarketing Sales Rule also bans misrepresenting any material aspect of a prize promotion, including the odds, the nature or value of a prize, or the fact that a purchase or payment is required to win.
Prizes are free.
If any payment or purchase is required, it's a sales transaction, not a prize. Others use an envelope that looks like it contains a telegram or government check. Don't be deceived by letters that look official or urgent. It's illegal for a telemarketer to misrepresent an affiliation with or an endorsement by a government agency or other third party. Read the letter carefully , including the fine print.