Three days ago I got a call where the caller ID said USF, which locally means University of South Florida. As my daughter had just graduated from there, I picked it up. But it was a home burglar alarm company calling out of Oregan (according to a Google search). I told them not to call again and hung up. I also filed a complain on them on the national Do Not Call Registry.
But today at 6:30pm they called again, but this time identified themselves as General Electric Home Security. I asked "Trayvon" the name the man gave me, if they were affiliated with the General Electric Corporation, and he said, "Oh yes! We are part of General Electric." So I asked him then why are they calling me since I'm registered with the Do Not Call? He replied, "Oh, well look at that." Then I said not to call again and asked him his full name. He said, "Oh sure...." and hung up. The caller ID this time said American Alarm. I reported it again on the Do Not Call list site.
The phone was 971-220-1656 and Google shows it as HOME SECURITY in Gresham, OR. So it's obviously the same outfit, masquerading as major companies or institutions to get you to pick up, and with no regard for the Do Not Call.
These guys are total scammers. Stay away. They just want your personal info.
Update 2019: Install apps such as HiYa and/or use your mobile providers Call Protection if they offer it.
AT&T's protection from spammers is Call Protect. Verizon and T-Mobil also have intelligent screening to prevent these unwanted calls on your mobile device.
It does almost no good to try to manually block each number since the robo callers used thousands of newly generated spoofed numbers and ID's.
Finally it looks like the telecommunications industry is responding with what should be the ultimate solution, a developing technology with the James Bond name STIR/SHAKEN.