The Federal Communications Commission voted on Nov. 16 to allow telephone carriers to block robocalls that appear to be fraudulent—a particularly annoying and costly problem that has mushroomed in recent years.

The ruling specifically targets calls that use so-called caller ID spoofing, which allows robocallers to manipulate information that shows up on caller ID to trick you into answering your phone. 

"If this will help protect consumers from getting illegal or unwanted robocalls, it's a good thing," says Maureen Mahoney, a policy analyst with Consumers Union, the policy and mobilization division of Consumers Reports.

Besides being annoying, the calls can put you at risk. Scammers often make robocalls to perpetrate fraud. The spoofing can make calls appear to be from the IRS, for example. The caller might threaten you with arrest unless you fork over your credit card information or wire money to cover nonexistent outstanding taxes.

Mahoney says Thursday's decision by the FCC is a step in the right direction, but she points out that only a small percentage of the calls will end up being blocked.

Others agree. David Frankel, a California-based telecommunications professional who has taken up the fight against robocalls, says his analysis of 3.5 million robocall complaints to the Federal Trade Commission shows that the new rules would block only 10 percent of robocalls, at best. And that would probably last for only a short period, he says, as robocallers no doubt change the techniques they use. 

"After six months, this won't do anything, mostly because the robocallers will work around it," Frankel says.

Still, the FCC's commissioner, Mignon Clyburn, said at Thursday's meeting that the new rules were needed. "Will the adoption of today's report and order put an end to unlawful robocalls for good? Sadly, no, but doing nothing ensures that things will get worse," she said.

Robocalls have been a growing problem for consumers and telephone companies. There were 2.5 billion robocalls made nationally in October, compared with just 683 million in October 2015, according to estimates from YouMail, a provider of voicemail and call-blocking services.

They're called robocalls because scammers, telemarketers, and others use automatic dialing equipment to place potentially thousands of calls an hour. Those who answer may hear a recorded message or be transferred to a live person who may try to perpetrate a scam, sell a shoddy product or service, or collect a debt, among other possibilities.   

No Silver Bullet

The FCC's ruling comes partly in response to a request from the telecommunications industry, which wanted to know whether it could block calls without breaking federal call completion rules, which bar phone companies from call blocking without customer authorization.

USTelecom, a trade association representing broadband service providers, supports the new rules.

"There’s no one solution to solving the robocall problem, but the FCC’s action today is another step in sweeping away the uncertainty about the tools available to providers to block these illegal calls," said a statement from the association's CEO, Jonathan Spalter.

Under the new rules, telephone companies can block some robocalls automatically without first getting approval from either the caller or those receiving the calls.

Among the calls that can be blocked are those showing numbers that have not been assigned to a phone carrier, are not in use, or are clearly invalid, such as those with nonexistent area codes.

In following the new rules, telephone carriers will have to be careful not to block legitimate calls. The FCC acknowledges that might be difficult because it's not always clear which telephone numbers are in use at any given time. Rather than make the rules mandatory, the FCC says it's hoping to encourage the industry to develop its own reliable blocking methods.

Frankel says that regulators could require carriers to place a cap on the number of calls a customer can place over a certain period without providing good reason. A single robocaller might make as many as a million calls a day, he says.

Consumers Union has been urging phone companies to offer their customers free call-blocking services such as Nomorobo, which intercepts calls that come from a list of known robocallers. Those services are becoming increasing available.

Tips to Handle Robocalls

Because the new rules won't block all robocalls, here are some steps you can take to avoid receiving them:

Contact your phone carrier. Many carriers offer services and blocking equipment that can help prevent annoying calls. 

Only answer calls from numbers you recognize on your caller ID. Mahoney cautions against returning a call using a number left by someone claiming to be from the IRS, a law enforcement agency, or your electric utility. The number could lead you back to a scammer. 

Require caller input. You can set up call-blocking technology, such as the Sentry Active Call Blocker and CenturyLink's "No Solicitation" service, to greet callers with a message requiring them to enter a number such as 0 or 1 before the call can proceed. (Nomorobo does this by default for suspected robocallers.) 

How to Deal With Robocalls and Robotexts

Annoyed by robocalls and spam text messages on your mobile phone? On the "Consumer 101" TV show, Consumer Reports expert Margot Gilman offers advice to host Jack Rico on how to deal with these spammers.