Does Call Block fully block, or send to Voicemail?

When a phone number is configured to be "blocked", is the call 1) completely blocked, or is it 2) sent to voicemail without the phone ringing?

Is there a way to configure this? Ideally I'd like some calls to be fully blocked and others to go to voicemail. But going to voicemail would be the preferred option if you can't configure by number. Sometimes "unknown" numbers are legit (such as an alternate number at a doctor's office).