@ceekay I signed up with nomorobo.com which is a free service for landlines. It has been great. Robocalls ring only once with no ability to leave a message on my answering machine. I look at the caller ID on my phone only after a second ring.
I do not use voice mail on my landline because it is too much trouble to call a number to listen to messages. Answering machines are far easier.
Not every single annoying call is caught by nomorobo, but I'd say 95% are. Today I had a message on my answering machine from a computer telling me this is my last chance to renew the extended warranty on my car...well, I've never had one, so this is another lying cheating enterprise. I also get some calls from a computer trying to sell health insurance. But it's very easy to push the listen button on my answering machine followed immediately by the delete button.
Anyway, I highly recommend nomorobo.