But the calls kept coming.
The F.C.C. hopes to get all providers, including smaller regional networks, on board. That would reduce spoofing by verifying calls as they pass through different networks, from the caller to the recipient.
While some robocalls are legal — such as recorded messages about school closings and political campaigns — most are not, according to industry estimates.
YouMail, a call-blocking company, estimates that 4.4 billion robocalls were placed to consumers in the United States in June, about 573 million of them auto warranty and health-related scams.
The scams often keep in step with seasons or events. On Friday, Katherine Fernández Rundle, the state attorney for Miami-Dade County, warned people about unsolicited calls from charities claiming to help the victims and families of Champlain Towers South, the condo building that partly collapsed in Surfside, Fla.
“Unfortunately, even in these most devastating moments, there are some individuals who may see the kindness and generosity of our community as a potential source of easy cash by running a charitable scam,” she said.
This year, there was a rise in vaccine-related scams. Health insurance scams appeared around enrollment periods, the F.C.C. said. The F.C.C. said it received the most complaints about auto warranty scams.
“Seeing a local number or the name of a government agency or local law enforcement may, unfortunately, encourage consumers to answer the call and to trust, or fear, the robocallers,” Will Wiquist, an F.C.C. spokesman, said.