STIR/SHAKEN has barely started to be rolled out, and most major carriers don't fully support both protocols. Realistically the reason you've not seen a difference is that... well there's not been a change. The TRACED act stipulated that large carriers have to have it implemented by June 2021 (and several have... mostly) and that smaller carriers have a 2 year extension until 2023. The problem is that "smaller carriers" has a much looser definition than you think, which includes the phone systems used by most corporate businesses and most cheap/easy SIP providers (like NICE inContact, OnSIP, RingCentral, etc). That said, it'll be a couple years before you see the silver bullet you're looking for, and even then it'll be a couple more before all the kinks are worked out. (There's still some unanswered questions about attestation in smaller regional/local carriers. Also international partners aren't complying with the standard, so that increases the complexity.)