It's sometimes hard to tell if a sales pitch is legitimate or fraudulent. You can't judge it by the tone of someone's voice, or how friendly or sincere the person seems.
Good salespeople are convincing, and so are crooks.
Legitimate sweepstakes or prize offers don't ask for payment because it's illegal. The person says you have to take the offer immediately or you'll miss the opportunity. Legitimate companies don't pressure people to act without time to look into the deal. The caller refuses to send you written information before you commit to anything. Legitimate companies are always glad to send information about what they're offering.