Administering an Asterisk/FreePBX system is one of my primary job responsibilities at the company I work for, an AEC firm based in my hometown. It has roughly 300 extensions with various inbound call flows including call flows, queues, IVRs, fax handling, paging, etc. We use Aastra, Digium, and Polycom phones as well as Cyberdata ceiling speakers. I have also connected in Lifesize video conference equipment to my system. I have built several sandbox PBXs as well and have moderate to advanced troubleshooting skills.
I don't know where your test lab is located but this is something easily done remotely via a VPN connection with an SSH putty session. If you give me a list of what exactly you need, like how many extensions, queues, how you want the calls to flow, etc, I can configure your system accordingly and then document everything into a call tree diagram, as requested.
I have a well-rounded skill set in VoIP with regards to FreePBX and Asterisk and I would be happy to discuss details further if awarded this project!