The chairman of the Federal Communications Commission announced plans today to battle the appearance of "mystery fees" on consumers' phone bills, a practice known as "cramming."

FCC Chairman Julius Genachowski said in a statement he would soon send his fellow commissioners proposed rules that are "focused on harnessing technology and transparency to empower consumers with the information they need to make smart decisions and to make the market work."

The addition of unauthorized fees--typically $1.99 to $19.99 a month--to consumers' bills affects 15 million to 20 million U.S. households a year, according to a survey cited by the FCC. The same survey found that only 5 percent of those consumers were aware of the monthly charges.

Last week, the commission issued fines totaling $11.7 million against four companies for allegedly charging thousands of consumers for long distance service that they had not ordered.

Genachowski said cramming erodes consumer trust in communications services.

"The FCC will not tolerate cramming, and we are turning up the heat on companies that rip off consumers with unauthorized fees," Genachowski said in a statement. "We want to send a clear message: if you charge consumers unauthorized fees, you will be discovered and you will be punished."

The FCC also posted a tip sheet to its Web site that encourages consumers to carefully review their monthly bills to prevent being overcharged.