WASHINGTON — After a barrage of consumer complaints, the government is banning phone calls of prerecorded sales messages unless consumers agree to receive the calls.

The Federal Trade Commission also announced yesterday that by December, all prerecorded calls must provide an opt-out selection to make it easy for consumers to stop getting those calls.

Effective Sept. 1, 2009, sellers and telemarketers may place prerecorded calls only to consumers who have provided signed and written agreements to receive them.

The FTC said the rules will not affect informational prerecorded messages, such as messages to notify consumers of appointments and cancellations, because they do not attempt to sell goods or services.

A report by the FTC said there were more than 13,000 consumer comments that objected to the telemarketing industry's request to gain more flexibility to make recorded sales calls.

The agency says the new rules will protect consumers' privacy, much like the Do Not Call Registry. The registry, initiated in 2003, has been widely acclaimed for allowing Americans to eat their dinners without being interrupted by telephone sales pitches. More than 150 million people have listed their phones on the registry, which prohibits calls from telemarketers, with some exceptions.

Mark Cooper, director of research for the Consumer Federation of America, said yesterday the rule closes a loophole that "was part of the intrusion of unwanted calls."

"Callers did not think they were bound by the Do Not Call list, and now they are," Cooper said. "The FTC finally addressed it."