Caller Verified uses the STIR and SHAKEN standards that are in place to combat illegal caller ID spoofing.
Right now, T-Mobile's implementation of Caller Verified is limited. It's only available on the Samsung Galaxy Note 9 and it is limited to the T-Mobile network.
On the Note 9, calls on the T-Mobile network will be "Caller Verified," with customers able to see that labeling to be sure that calls are authentic and are not coming from a scammer or spammer.
T-Mobile says that it plans to make the Caller Verified feature available on more smartphones later in the year, but it is not clear if that includes Apple's devices.
The feature will also work with calls coming from other carriers once other wireless providers implement STIR/SHAKEN standards.
T-Mobile has other spam fighting tools including Scam ID, Scam Block, and a premium Name ID app.