The spammers have refunded more than $25,000 and have agreed to federal oversight of their business activities, the Federal Trade Commission said.
According to FTC charges filed in March 2002, Internet users received an e-mail message saying they had won a Sony PlayStation 2 in a sweepstakes contest sponsored by Web portal Yahoo.
Those who responded to the message were directed to a fake Yahoo page that instructed them to download a program that would allow them to claim the prize.
The program then connected them to a pornographic Web page that secretly charged them $3.99 a minute through a 1-900 telephone line, the FTC charged.
BTV Industries, which created the modem-dialer software, has returned $25,000 in gains from the scheme, the FTC said.
Three individuals--Christopher Baith of Pennsylvania, Cosme Monarrez, Jr. of Las Vegas and Sorabh Verma of New York--have also promised to avoid such schemes in the future, and Baith will return $2,500 in gains, the FTC said.