I've been getting these call for several years.
This what I've found to be pretty effective.
I made a list of spam callers phone numbers and when one of them call, I answer with
AN INDIAN ACCENT AND SAY HELLO, HELLO, HELLO, AND I DO NOT IN GAGE IN CONVERSATION WITH THEM. This drives them crazy and they hang up.
Mission accomplished! Then they put me on their DO NOT CALL LIST. !!!! I win.  

Now, those call have dropped off a lot.
It works for me, Try it You'll like the results.
9/6/13

Thanks for letting us all now. Now we can understand how this caller can afford to make so many calls to many people in a day. Somebody is working hard to make sure he becomes the new mayor...

Answered a call from this number... It was a woman from the Leland Yee for mayor campaign.. Asked if i've voted and when I said yes she just hung up on me. F#>|"!G rude!

I picked up a call from this number and it was a lady named Melissa from the Leland Yee campaign. She asked if I've voted and when I said yes she just hung up. Rude rude rude.

Me too, just received a call from the same number, when I answered the call, no one on the other end.

I receive multiple calls from this phone number everyday. If I don't pick up then no voicemail is left and when I do pick up no one answers and just hangs up. When I call back, no one picks up the phone. It is starting to become an annoyance and honestly quite creepy. It's good to know I'm not the only one, but I wonder how they even got our phone numbers to begin with. It might have something to do with the elections...

Same here... annoying. continues to call, never leaves a message. And when I call the number back, it is busy. I am on the Do Not Call Registry and this is annoying.

I've been receiving a call twice a day during the afternoon.  Nobody is on the line and nobody leaves a voice message.

Have received 3 calls from this number in the last 4 days. I never answer and no VM is left. I've added it to my "Wrong number" contact which has silent ring & text tones configured so it doesn't bother me anymore.

Several calls, once or twice a day, since last Thursday.

Calls at least once a day. Very annoyed.

I am getting really annoyed at this number!!!! It calls me every single day! I want it to stop.

I have been getting these calls for about two weeks now.

If I pick up, no one speaks. If I let it go, a blank VM is left.

Just received a call from this number whilst on the other line.
No voice message left.

Calls a lot but never speaks.

I have been receiving calls from this number daily, usually between 11AM and 1PM.  The calls started on 10/18 and have almost never missed a day.  Yesterday, there were 2 calls.  I never answer and there is never a voicemail.  When I've called back it either rings without an answer or it rings busy.

This number calls me repeatedly and I let it go to voicemail. They never leave a message. Today when I actually answered the call. A male voice addresses me in Cantonese using my actual name. When I said, "Speaking." The guy hangs up. When I call the number back, there is no answer or it is busy. Now I'm a little worried.

Just received a missed call from this number, did not leave a message.