Also, filtering on a waveform is much harder than text data.

Filtering on a waveform that doesn't exist until the user picks up the phone is literally impossible.

What does this even mean?

It's hard to use automation to tell if the phone call you're receiving is a Medicare spam call, or a genuine call about Medicare for example.

"I buy junk cars" is pretty easy to filter out. Nowadays they send things like "i/buy/any old/car Yconpro/autos*" (this is a real one I got 9 hours ago). But that's still easier to design a filter for than a phone call which only happens over audio.

They should be able to recognize spoofed numbers though. More than 90% of spam calls I get are clearly coming from a spoofed number. Sometimes it's even my own number.

I know the current infrastructure can't really deal with that, but it's because the telecoms have no real reason to implement it.

That’s interesting, I have never seen that. I get almost all of my spam from VoIP numbers in the same area code as my number.

Clearly spoofed as it’s not the IRS or the number is too coincidentally close to yours?

My employer seems to have gotten a lot of sequential phone numbers assigned, so a similar number used to be highly correlated with legitimacy, now it’s a mixed bag.