How to Send Unknown Callers to Voicemail in Google Voice? [Solved]

We assume by unknown callers you mean people who are not in your address book?

Go to Contacts (in Google Voice or Gmail), and put all your contacts into one or more groups. Then go to Settings | Groups (in Google Voice),  and customize each group, making sure to specify that they ring all your phones (or less if appropriate). Then go to Settings | Phones, uncheck all the phones there. Now everybody who calls you who is in one of the groups will trigger the phones to ring, while anyone who is not will go straight to voicemail.

Note that this means that any contact you add should be placed in one of those groups. Also the contacts should have their phone numbers populated. If they are not populated, then Google Voice won't know it's your friend calling and will send them straight to voicemail.

Another simple way to send unknown callers to voicemail in Google Voice?

So every time I add a new person to my contact list, then we also have to remember to add them to this arbitrarily created meta-group? Yuck. What a horribly inelegant and inefficient solution. This is an abomination.Isn't there a better way? 

We want to send only certain telephone numbers automatically to voicemail (not block them completely). These are numbers such as telemarketers, my bank, health insurance company, etc. we don't want to talk to these people. But at the same time we don't want to miss their calls completely. If we wanted to block them, I could simply click "Block Number" without adding them to my contact list. But if we want to send them directly to voicemail, we have to clutter up my contact list with them? WHY??