FreePBX (Asterisk) Email Based Conferencing System
FreePBX is a feature rich administration GUI for Asterisk and the conferencing module is great for static conference rooms. How about dynamically creating conference rooms by email?
Asterisk Articles
Asterisk and MySQL on Debian Wheezy (7.0)
Extend your Asterisk setup with MySQL so you can better integrate your phone system with existing applications (not just for call record keeping).