Hi,
I have been working with Cisco VoIP since 2001 and Asterisk and freepbx ,trixbox, elastix since 2007.
for reference : I have recently implemented a nagios based monitoring setup to monitor around 30 Asterisk servers for a client on this freelancer.com website.
That being said I would like to have a little chat about your project to better understand the needs of the project.
regards,