hey guys im doing my last year of my Networking degree adn have decided to do my project on VoIP PBX systems. I have decided on a simple topology as follows in the attachment. I have installed 3CX phone system and have configured it with the windows management console, i have PC 0 (vlan 10) and PC 1 (vlan 20) connected and have each softphone talking to each other using the PBX server (3cx) which is fine and good BUT what i need or would like to know is if it is possible to install a second PBX on a virtual drive or second PC that will act as a backup PBX in case the first goes down to offer redundancy. It should be able to backup the phone numbers stored and the users (softphones) should not see more than one PBX ever. Is this possible and since its a project i cant spend any money on it :S please help guys!!! Seriously stuck as i have never done VoIP before this project xD Any and all help will be greatly appreciated!