Washington ? More than 30 million Americans have signed up for the government’s do-not-call list, a free registry for blocking unsolicited telephone sales pitches, the Federal Trade Commission said Wednesday.

“Millions of consumers registered their telephone numbers successfully within the first few days of the opening of the registry, and hundreds of thousands of numbers still are being entered every day,” FTC chairman Timothy J. Muris said. “We want to do everything we can to make certain that consumer expectations about the registry are met.”

Telemarketers have challenged the list in court, saying the registry will cost them $50 billion in business and cause the loss of 2 million jobs.

Beginning in September, telemarketers will have to check the list every three months to see who doesn’t want to be called.

People can register for the service by calling (888) 382-1222 or visiting www.donotcall.gov.