the largest concern is usually bandwidth. second would be management of devices in the system. email me at: email@example.com and I’ll help you do a layout and send you more information that might help you better understand what needs to be done and what hardware you need.
good luck with a project that big.
I can help you with the VoIP part, but integrating networks ( data ) would not be something I would be able to handle..
Can anyone help with the Data and I could help with the VoIP?