Hi,
I have been working with Cisco VoIP since 2001 and Asterisk and freepbx ,trixbox, elastix since 2007.
I also have a very good experience in developing software using Vb and PHP,
I can give you a demo of some basic wall board on one of my demo servers,
That being said I would like to have a little chat about your project to better understand the needs of the project
regards,