Wireless phone companies are taking a big step forward to block the scourge of the industry: spam robocalls.

Verizon is exchanging information with AT&T and T-Mobile on every call to help verify that the listed caller ID number is accurate. The effort, which also includes Comcast, should help the carriers automatically block many robocalls, since a common tactic of scammers is to display a fake caller ID to trick consumers into answering.

Despite laws intended to ban unwanted calls, robocallers peppered Americans with an average of 159 million calls per day last month, estimates YouMail, a robocall-prevention service. The auto-dialers range from legitimate companies to harassing debt collectors to outright criminals. Scams accounted for 48% of the calls, particularly involving fake extended-warranty deals and phony health-related offers.

News of the industry effort came as the Federal Communications Commission separately announced on Wednesday that it fined a robocalling telemarketing firm $225 million, the largest fine in the history of the agency. The Texas-based firm was making millions of calls per day with fake caller ID information while falsely claiming to offer health insurance plans from well-known companies like Cigna.

The pace of robocalling declined during the COVID-19 pandemic, but since the start of the year it has rebounded to the prior levels. The telecom set's new collaboration covers more than 24 million calls per day exchanged between the three major wireless carriers and Comcast, according to industry officials. The plan is to continue expanding and including other smaller carriers as well.

“There is always more to be done, but this is yet another important step for the industry," Ronan Dunne, Verizon's CEO of consumer business, said in a statement. "Customers should rest assured that we remain vigilant in our efforts to take down the bad guys and protect them.”

T-Mobile vice president Grant Castle emphasized that the goal is to include all carriers in the data exchange. "We are currently working with almost every other wireless provider to help keep consumers safe from scammers at this critical time,” he says.

"We work daily to stop unwanted and illegal robocalls from reaching consumers," a spokeswoman for AT&T says. "Along with other providers, we’re continuing to implement STIR/SHAKEN call authentication. It helps confirm that a call is not illegally spoofed."

Fortune reached out to Comcast for comment and will update this story if it responds.

To combat robocalls, the carriers are relying on an anti-spoofing standard with an unwieldy name: "secure telephone identity revisited" and "signature-based handling of asserted information using tokens." More commonly, people call it the STIR/SHAKEN standard. Ensuring accurate caller ID labels on calls helps prevent scammers from faking the information, though the strategy does not help block a call if the scammers use accurate labels.

Two years ago, the Federal Communications Commission voted to require use of the standard after the industry failed to adopt the measure on its own. Still, despite the latest cooperative moves, the robocallers have proven adept at evading nearly every effort to cut them off from reaching consumers' phones.