I have an algorithm for this
1) The phone rings. I pick it up. Silence on the other side (caller bot). -> Blacklist
2) The phone rings. No Id. -> The phone doesn't ring. I disabled calls without ID.
3) The phone rings. I pick it up. You try to sell me something. -> Blacklist.
4) The phone rings. I pick it up. Telemarketing. -> Black list.
5) The phone rings. I pick it up. I don't like you. -> Blacklist.
Yes, the blacklist is getting quite fat, thanks for asking.