Modern technology has given telescammers the tools to call you.
Since those telescammers are criminals, they ignore both the Do Not Call list and any request you might make.
Modern technology can also protect you, if YOU do a few simple things!
The first thing to do is buy a call blocker device, service or app.
Then, use it correctly.

Google "call blocker" for more information.
http://goo.gl/cdPm8O or http://gg.gg/blockers

If you cannot afford or use such a tool, then:
* Do not answer calls from unknown numbers ... let them go to voicemail or answering service
* Do NOT return calls from unknown numbers!  All that does is verify your phone number!  And, in some cases, those return calls may cost $20 or more to complete.
* If you have a "dumb" cell phone, assign the scammer's number to a group named "scammers" (or similar).  Then, assign a silent ringtone to that group.

This number is still robo calling.  Similar pattern to that listed previously.  I have 5 calls just today. If you call back, you get elevator music. No VMs ever left.

unwanted calls

Received 48 calls over the past 3 days from this number from morning to evening to my cellphone.
Now getting calls from this same number on a second unpublished line starting early morning (And this is on a Saturday).  They are also spoofing caller ID and at times shows up as Campbell, CA.  answered once and it was live - sounded like a boiler room type of telemarketing.

This phone number calls every 10 minutes and never leaves a voice message. It's been non stop for the past 3 days.

keeps calling a few times a day, no one on the other line just silent,