Effective June 30th, 2021, all phone carriers are required to implement a policy nicknamed Stir/Shaken. It’s a method to determine if Caller ID numbers are “signed” as legitimate at their originating location and to validate the Caller ID as calls pass from carrier to carrier.
It’s unclear if this will actually help eliminate robocalls, because some carriers have already implemented the policy. And, these scammers are always working to find new ways to harass us.
There are more details at https://www.cnet.com/news/robocalls-are-out-of-control-that-could-change-after-june-30/.