is there any reason to believe this is anything other than the next step in a long, slow-moving process? SHAKEN/STIR has been being rolled out for a few years now, IIRC most major players said they were going to have it deployed by the end 2019 (see response column of table towards the bottom of https://www.fcc.gov/call-authentication), now they're just setting a deadline of June 2021 to start authenticating calls.