VoIP Cookbook: Minimal requirement / configuration

Use 100 Mbps LAN switch hub with dedicated segment.
Use Gigabit Ethernet to switch / router that connected to the server.
Use a good IP Phone, it may be beneficial to use a switch that can prioritized voice traffic.
Talk to your ISP, make sure we receive enough bandwidth. It would be beneficial if the ISP can prioritize Real Time Protocol (RTP) traffic.
Make sure the router may prioritize RTP traffic.
Make sure the firewall is configure to pass VoIP traffic.
Design a management and monitoring infrastructure to help quick problem detection and solving.
Do test prior to system operation.

See Also