Yes something is blocking you from getting packages. My Guess is firewall or DNS resolution. When going through the network setup make sure you are defining good DNS severs that can resolve yum.freepbxdistro.org
Just tried now from my home, without firewall or filter… downloaded new ISO… and same error… see the screenshot here : http://www.megaupload.com/?d=MSVNTJ3X
Similar error I was getting when I had connectivity problems. Sorry I can’t help more then that. Is your DHCP server giving it an IP address? Can you ping it from another machine?