I am using SLNet to network a couple of SL1100 - will be adding more to the setup in the future. Works good over VPN. Sounds like you want to just network a couple side-by-side to get the # of SLTs you need. I would think that would work fine as well. Not sure if the cost of the VoIP cards and licenses would make it a good decision - or if it would be better to go up a step like Coral Tech is suggesting...........