I do not answer calls from numbers I do not recognize. Anyone who knows me knows that if they're calling me from an unfamiliar number they'll have to leave me a message. These types of numbers, and even though I've checked and I'm still on the DO NOT CALL list, have been appearing more frequently lately. They never leave a message so my guess is they are illegal telemarketing calls.
I got a call from this number this morning. They didn't leave a message. I called back and the recording I got was "the survey that we were calling about has been completed."