* T-Mobile, like the other carriers, is offering a numerator and not a denominator. These call filtering services are plainly valuable, but it's difficult to evaluate how effective they are based on current public evidence.
* It isn't a coincidence that the top robocall destinations include locations that are popular for retirement. These scams disproportionately target and take advantage of older customers.
* Call authentication (STIR/SHAKEN) is helping, and will continue to become more effective. The FCC did not push carriers to rapidly adopt call authentication during the last administration; Congress eventually stepped in with the TRACED Act, and the FCC has since made STIR/SHAKEN a top priority.