The Federal Communications Commission, trying for a second time to make it tougher for children to hear pornographic telephone messages, adopted a system on Wednesday that requires use of special access codes or prepayment by credit card for such a service.
The rule becomes effective 30 days from the date the order is published in the Federal Register.
Many of the operations, which offer sounds of actual or simulated sexual behavior to anyone who calls, are reached by dialing special phone numbers. The phone company charges extra for such calls and splits the money with the service.
The commission said that its regulation "represents the most effective available means to limit minors' access to the messages but, at the same time, offers the least restriction on adults' access."
Last November, a federal appeals court in New York City ruled that an earlier FCC dial-a-porn regulation was unconstitutional.