Answered "Hello" 3 times no response back. WTF?

I have received 3 calls from this number this week. 2 were while I was at work. When the third call was made at 11:45 a.m. on Sunday, I picked up. The caller waited until I said hello and then hung up. I am on the "do not call" registry.

Calls several times per day. No answer or leaves no message...

I.D.'d as Ziff Davis - I answered and after a short delay (probably a predictive dialer) a lady asked to speak to a person who was not here at the moment. I asked her who was calling, she gave me a female name only, and curtly asked again if the individual was available. When i offered to take a message, she curtly told me she would call back, and hung up.

This was a legitimate call from Thoroughbred Research. They were calling to follow up on a call I had made to the gas company regarding a gas emergency. They asked me if I would voluntarily do a survey based upon the customer service I received. They were very courteous and it took only 10 or 15 minutes, and I wanted to give the feedback

tries to get you to connect by pressing option 1 says its your last chance to lower your crdit score.. yeah right,,,,lol dont answer it scam!!!!!!!!!!