A new F.C.C. rule is meant to help cut down on robocalls.

Americans get millions of illegal robocalls every month, despite attempts by the telecommunications industry and government agencies to stop them.

The Federal Communications Commission — the government agency that regulates communications — is trying to cut down on the calls with new rules that went into effect on June 30, Christine Hauser reports for The New York Times.

Here’s how it works.

• In short, the F.C.C. is trying to make sure that if you’re getting a call, the network on which it is being made is verifying the caller.

• The F.C.C.’s first step was setting a June 30 deadline for what it calls “voice service providers” (you know them as phone companies) to register their efforts to reduce the scourge of scams in a public Robocall Mitigation Database. So far, more than 1,500 of them have, the F.C.C. said.

• Starting on Sept. 28, phone companies must refuse calls from providers that have not registered with the F.C.C.

The F.C.C. hopes to get all providers, including smaller regional networks, on board. That would reduce spam by verifying calls as they pass through different networks, from the caller to the recipient.

This will help stop some scammers from manipulating their number to make the call appear more legitimate. But some businesses legitimately change the number displayed on caller ID to show their switchboard number or toll-free number, rather than a specific department or extension.

“The key thing here is it was never intended to be a silver bullet,” one analyst said of the new effort. “It was intended to be a tool to help.”