Received call on mobile phone at 3:00pm 6July2017, and let it go to voicemail. No VM left. Called the number on the office land-line, and was a busy signal. Called back at 3:04 and there was no ringing just an immediate message that said "press 9 to be put on the do not call list." Pressed 9, but no sound or confirmation, just silence.
Have blocked on my mobile phone.
Similar to Matt S, I received the identical voicemail: "Press 9 to be put on the do not call list." I strongly suspect this is some kind of scam and have also blocked the number.