Time is Money

Everyone that keeps the fraudster on the phone for 3 minutes or more (without buying anything) can enter to win a $1,000 monthly drawling. This will drive the costs up to the point where it is no longer profitable and the calls will stop. Even after the monthly drawings end, the public will be in the habit of messing with them this way.
This will be advertised mostly to college student. To enter the user would go to a web site and enter their phone number along with the fraudster’s number. The winner can confirm the call with their phone billing statement.