I am going to take one of the spare servers that I have and setup a Asterisk based system to play with. I am trying to figure out wich version of Asterisk to install.
Asterisk http://www.asterisk.org/ This is the grand daddy of all the version. This version requires you to install everything and most likely is the hardest to deal with.
Tribox http://www.trixbox.org/ This version was formery known as Asterisk@Home and has evolved into a fully capable PBX system. This system comes can be downloaded as an ISO an when burned to a CD and booted on a system will setup CentOS and the Asterisk software. Configuration is easy with the supplied gui tools. Other features and software include trixbox dashboard, Asterisk(tm) Open Source PBX, FreePBX web management tool, SugarCRM, Munin (via package manager), HUDLite server/admin (via package manager), IVRGraph (via package manager), phpMyAdmin (via package manager) and Webmin (via package manager). Lastly they offer a pre-installed system theat you can buy and rack up.
Easy Vox Box http://easyvoxbox.org This is also an ISO version. It seems to be an exact copy of Tribox. Its features include; Asterisk, Asterisk Developer Docs, freePBX, Access Control, Asterisk Recording Interface, Flash Operator Panel, MeetMe Control Center, System Status, System Info, Asterisk Info, MySQL, phpMyAdmin, Config Editor, Centos, Telephone Reminders, Easy Web Call.
Right now I am inclinded to go with Tribox just beause it seems more mature. My next steps are to find a VOIP termination service and perhaps a hardware phone to use.