PaulDavis too late to edit.
Another feature is that you can block by prefix sequence, so you could block by country, state, city, company (where they have many numbers in a sequence), block mobiles by their network code, or if you really want, by the individual number. You could even block using words from their name, just in case a branch from a different town calls you.
But if your doctors etc are withholding their number, then hound them to get an outgoing only number for the switchboard