This is a staged "prank" by William Moreno himself to throw the heat off of himself that he's been the one harassing Megan and spoofing numbers. I got a similiar voicemail to Megan's from William Moreno. 1am, 2am, 3am phone calls, from him then from a Florida number after I didn't answer.
http://vocaroo.com/i/s1mbq7HWDs9V
"You there?"
and you can hear him say "You gonna do it? I guess she's not answering"