I'm in the process of installing Trixbox which is the new version of Asterisk@Home. It seems some things are not enabled by default, like voicemail. Also, it would seem SCCP is missing some stuff to install. I found this maillist entry that sums up the steps pretty succinctly. So far it LOOKS like it's working but I haven't tested it to be sure. I'll report back after I know it works.