Americans plagued by billions of unwanted robocalls to their phones are about to get some relief.
The Federal Communications Commission has approved rules to make it easier for carriers to stop automated calls.
Phone firms will use algorithms and network scanning to block calls in the way that emails are screened for spam.
It won't stop all calls - and customers can opt out - but the regulator says it will help with the some 5 million robocalls a month consumers receive.
Says FCC chairman Ajit Pai: "There is one thing in our country today that unites Republicans and Democrats, liberals and conservatives, socialists and libertarians, vegetarians and carnivores, Ohio State and Michigan fans: It is that they are sick and tired of being bombarded by unwanted robocalls."
Although some phone carriers offer blocking functions on an opt-in basis, the FCC will let telecom operators make it a default option.The communications regulator will also allow companies such as AT&T, Verizon and T-Mobile to offer customers the choice to block calls from any number that is not on their contact list or other approved numbers.
FCC commissioner Geoffrey Starks said action was urgently, adding: "Put simply, by allowing these calls to proliferate, we've broken the phone service in this country."
The crackdown would free up network capacity and cut the number of consumers being scammed by criminals, he said.
However, there is no requirement to make telecoms companies provide the call-blocking service for free. Mr Starks said he would have "serious concerns" if they started charging.
The major carriers welcomed the FCC's move. Verizon said it meant "we'll be able to provide our customers the benefits of spam alerts and blocking more broadly and conveniently".
Apple announced this week that its new iPhone operating software would give consumers the ability to allow only calls to ring from numbers in contacts, mail, and messages and send all others to voicemail automatically.
Last year, a man was fined a record-breaking $120m (£88m) for making more than 90m automated marketing telephone calls in the US.
Miami salesman Adrian Abramovich was accused of trying to sell holidays and timeshare properties with the unsolicited robocalls.
The fine was the largest the FCC had has ever issued.