A robo-call scam...how do I block this number?

RECEIVED SECOND CALL FROM SCAMMER--HUNG UP ON HIM- PUT INTO CONTACTS AS A DO NOT ANSWER

"Uh, this is John from shipping, your alarm is already paid for..." scam robo call
Caller ID: "Not Available"

This one's slick, I actually thought there was a live person on the line. I could hear him flipping the pages of paper he was reading and I was all set to "play" with the caller when I realized that it was a recording. I wish I had a nickel for each time he said "...uh..."  Following is the text of the recorded "conversation"...

"Hi, uh, this is John from the shipping department of Emergency Medical Alert, I was calling to uh schedule a delivery of your medical alert system, it's uh the "fallen, and I can't get up" type of system you've seen on TV. Looks like the system's been uh recommended by thousands of hospitals and medical professionals, uh, let's see, says here that the system's already been paid for. Looks like you're getting the system because uh either yourself, a friend, a family member or maybe even someone you know has experienced a fall in the past so uh again it's already been paid for so there's no cost to your whatsoever. Also says here that the shipping has already been paid for so to uh schedule the delivery of your Emergency Medical Alert System press 1 uh again to uh have your system shipped out to you press 1 now...press 5 to decline the shipment of your system....(me) Hello?"

Thanks to Google Voice ( www.google.com/voice ) you can hear our conversation on my Spam Calls web page:

http://home.comcast.net/~achx88a/spam/spamcalls.htm


Signup for your own free Google Voice account at www.google.com/voice and avoid telephone call spam

Received call on 8/17/13 at 9:20 a.m.  Caller ID said Sema Recovery Group.  I did not answer and the caller did not leave a message.

Sema Group recovery = scam!  

What is the point of the Do Not Call registry if it does not work?