If it ever goes into effect, the national "do-not-call" list will almost certainly mean big layoffs at telemarketing companies, where employees already hang from one of the working world's lower rungs.

Some 2 million of the 6.5 million Americans who work in the industry will lose their jobs, according to the American Teleservices Association (search). It based its estimate on the Federal Trade Commission's prediction that 60 million Americans will eventually add their home telephone numbers to the national do-not-call list designed to protect people from sales calls.

According to the association, 64 percent of telemarketers are minorities, 30 percent are recent recipients of some kind of public assistance, 26 percent are single mothers and 5 percent are physically disabled.

"These are folks who are not going to find it easy to find a job," said Tim Searcy, the group's executive director.

The Direct Marketing Association (search), another industry group, asked its member companies to stop calling households on the list starting next Wednesday, even though a court battle over its legality may not be resolved by then.

A federal judge in Denver on Thursday blocked the list on free speech grounds. FTC Chairman Timothy Muris said Friday the agency will fight the decision, backed by new legislation rushed through Congress giving the commission more power in the matter.

There are about 166 million residential phone numbers in the United States, and telemarketers attempt up to 104 million calls to consumers and businesses every day, according to the Federal Communications Commission.

Some telemarketing companies, such as Atlantic Tele Center, which operates in Guyana, already have laid off employees in anticipation of the registry.

Some telemarketing services that make calls on a contract basis for other businesses have said they will close down rather than spend the thousands of dollars necessary to upgrade systems so they can comply with the new federal regulations.

"I think it probably will hurt some companies, and particularly the smaller operations would have a harder time absorbing the economics of adjusting to the latest regulations," said Brian M. McCutcheon, founder of SoftReach Services of Gilroy, Calif., an independent consulting practice that has helped some companies satisfy the latest government regulations.

But he noted that some experts think the lists may actually help telemarketers by saving them from calling people who are unlikely to accept their offers.

Some companies insist the effects will be slight. They say most of their business comes from inbound calls, or from outbound calls that are not targeted by the regulations, including calls made to existing or former customers. Companies may continue to call people on the list if they have done business with them in the last 1 years.

These are not new hurdles for many telemarketing companies. Already, more than two dozen states have implemented their own do-not-call lists — some of which have more stringent guidelines than the FTC's.