I have a IPO 500 and 3 IPO 500 EXTN PHONE CARDS(8 Ports). I will be using the network provided on site(just cable internet), there is no firewall, I'm using Broadvox for my SIP provider and also I have my SIP license. Do I need any additional hardware/software to make this work? With that being said the documentation I have has little details on configuring this unit. Any help would be a greatly appreciated.