T-Mobile was one of the first to adopt SHAKEN/STIR technology to validate whether an incoming call was legit. At the time, it only worked for calls within their network. I don't know if they have expanded the use to all calls. A good overview of the technology can be found here:
This whitepaper provides a basic introduction to the STIR/SHAKEN call authentication framework.
transnexus.com
It will take some time before every incumbent exchange carrier supports it and doubtless much longer for VOIP carriers to adopt it. I see trouble on the way for find me/follow me when you are only allowed to send your own telephone number into the network. An incoming call that is then forwarded out to your cell phone would likely be rejected since the calling number is not registered to your account. I'm sure there will be a lot of drama as the new standard is implemented. Changes in the way the phone companies, VOIP carriers and PBXs operate will all result in some pain before the bugs are worked out.