Actually, there is a (small) bit of hope: SHAKEN/STIR [0]!
> STIR/SHAKEN, or SHAKEN/STIR, is a suite of protocols and procedures intended to combat caller ID spoofing on public telephone networks.
> ...
> As of 2019, SHAKEN/STIR is a major ongoing effort in the United States, which is suffering an "epidemic" of robocalls. The Federal Communications Commission is requiring use of the protocols by June 2021.
> STIR/SHAKEN, or SHAKEN/STIR, is a suite of protocols and procedures intended to combat caller ID spoofing on public telephone networks.
> ...
> As of 2019, SHAKEN/STIR is a major ongoing effort in the United States, which is suffering an "epidemic" of robocalls. The Federal Communications Commission is requiring use of the protocols by June 2021.
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[0]: https://en.wikipedia.org/wiki/STIR/SHAKEN