This has been a problem far longer than cell phones or spoofed numbers. I don't want to have to individually block every one of the 8000 numbers some scam telem

This has been a problem far longer than cell phones or spoofed numbers. I don't want to have to individually block every one of the 8000 numbers some scam telemarketer paid to have allocated. I don't think your plan mitigates any robocalls, it just forces them to (slightly) change tactics.