Caller ID Sunnyvale CA. Hangs up and leaves no message. Call preceded by 'Unavailable' with no number ID an presumably to validate your phone number and test blocking. Typical scammer/political solicitation/harassment tactic.

Rings 3 times, and hangs up; no message.  I blocked my CID and called it back, some guy answers.  I decided not to say anything and just waited in silence... he said hello a few times, and hung up,...  I am not sure, I feel somewhat satisfied that I got to reverse the roles here...  taste his own medicine.

Calling numbers back doesn't help matters, in fact can make them worse. Its bad because the numbers are spoofed as a ROT. You could be calling some innocent persons number or a innocent business that had nothing to do with the calls. While we understand that is is a frustrating thing, its just a bad idea.

phone spoofing explanation
http://en.wikipedia.org/wiki/Spoofing_attack
http://www.fcc.gov/guides/caller-id-and-spoofing

http://800notes.com/forum/ta-9f0ce767d8019be/a-different-spoofing-victim

http://consumerist.com/2014/03/18/florida-den ... y-telemarketer/

Consider buying a call blocking device or phone. Many are around $50.00 and can block up to 1500 numbers. If its a cell phone, some already have call blocking, if not, there are free apps on the web that will work for some. You can google this. If u have a smart phone, there is a free app called call control. Iphones appear to have apps also.

Report your callers here:

By State DNC lists:
http://800notes.com/res/DoNotCall.aspx

Federal:
https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2
http://www.consumerfinance.gov/complaint/
http://www.stopfraud.gov/report.html
http://www.fraud.org/

the do not call complaint list is a joke..I file may a complaint on some of these callers and  a year later they still call..it even says on the complaint form that they just take information..u

The DNCR is not a call blocker.