I have been getting calls from them as well. It looks like they are verifying numbers, who goes voicemail, picks up and calls back. Get enough numbers and sell it at auction.
they said something but they said it so fast I couldnt make it out..and then they hung up..However it certainy wasn't an apology or anything like sorry I dialed the wrong number. I don't want them calling and calls have been coming in all week from other cities to which they don't answer when I say hello..they listen for a moment and then hang up.