There was a rich set of features around this in Grand Central that Google removed when it became Google Voice. There were options for having people not in your

There was a rich set of features around this in Grand Central that Google removed when it became Google Voice. There were options for having people not in your contact list have to go through a phone tree (that you could customize) before being allowed to make your phone ring. Grand Central getting bought by Google was the worst thing that could have happened to it. So sad to see an amazing service nerfed.