As a former radio broadcaster, I wrote and voiced the following outgoing message for my answering machine.  It didn't work completely but did reduce the number of robo calls I get by about 70%:

"If you are a telemarketer please me from your list and GO AWAY.  If you want _____ (me or a fictitious name like Joe), leave a message"

Just had my turn - checked out this website and pushed "BLOCK" on my call blocker box. Thanks everyone!

Called at around 2:30 PM...kept saying hello just to see if someone would come on the line - something about lowering interest rates...man finally came on and was absolutely vulgar, swearing up a storm, calling us incest, a$$holes, f*ckers, telling us someone told him to "lick their p*ssy" and called my grandmother a s**t. I am absolutely furious.

This number just called - did not pick up--no message----Scammer  i,m sure---been called by this number before--??!!

got robocall from 206-397-1895 caller ID said "UNKNOWN NAME" on Tuesday 02-04-14 @ 1038 AM.

Call starts out " Dont hang up..........Discover card......Press 1 or press 2 to be removed. Pressed 1 and gal came on the line
said can get rate as low as 9.9%. Asked her "what about the Discover Card that was mentioned?" She said it depends it could be a Visa Master Card etc. She then asked "how much do U have in credit ?" I gave her a bogus amount of $15K.
She then continued to talk but I gave her continued blasts on the "SCAMMER HORN".
She bailed real quick

It's a robo dialer, blocked by my service.

Called Land-line at 10:34am Eastern Time. Rang five times and stopped.

I don't pick up calls that say "Unknown Name" and I don't have an answering machine due to this type of call harassing us all the time day in and day out.

Call Type: [Most likely] JUNK!!!

Just called, didn't pick up, no message left.  Haven't blocked just yet but already assuming this is a CC spam bot.