Hi,
I have been working with Cisco VoIP since 2001 and Asterisk and freepbx ,trixbox, elastix since 2007.
as far as i can understand there can be two three issues with your server.
I have installed and fixed this kind of errors before, you may find some of the projects even in my freelancer profile as well.
That being said I would like to have a little chat about your project to better understand the needs of the project
regards,