If software can do this, software can easily parse your message and generate a tone:
https://www.youtube.com/watch?v=ufBLI6bB9sg
https://www.youtube.com/watch?v=hPXS7rC1PWo
https://www.youtube.com/watch?v=9I20frbeawg
And software can do that. ALL of the videos above show real world current commercial product capabilities. You can buy them right now.
And you think a little voice greeting directing the caller to press zero is going to stop this kind of software?
As soon as you buy a new car or computer and get home with it, it’s obsolete. That’s life. The Sentry is, IMO, the best thing avaibloe for call blocking and it works perfectly.
I don’t what burr is under your saddle, but letting the perfect drive out the good seems to be part of it.