Step #5: Verify that quality of service (QOS) is supported
Verify that QOS is supported on all segments and devices over which the VOIP traffic will travel. If latency, jitter and packet loss are the most common ills that plague VOIP systems, QOS provisions are the most effective vaccine. You should never rely on the accidental fortuity of your network infrastructure to ensure timely and reliable delivery of media packets.
Configuring network devices to prioritize RTP packets is like taking out health insurance for your VOIP calls. To lay the groundwork for VOIP, you must confirm that each network device is capable of understanding and complying with QOS parameters in packet headers. Without QOS, your VOIP packets are just "part of the crowd" on the network. With QOS, they are given VIP transit authority from their source to their destination and audio quality is safeguarded.
Only when all of these topics are addressed can the feasibility of VOIP be assessed. The outcome of these analyses may indicate that VOIP can be supported. However, the results may point to aspects of the network that need to be modified before they will be truly ready for VOIP.
While all of these steps might seem like a lot of work, they are the only means to assure that your VOIP system will not be crippled by adverse network characteristics. Once VOIP is deployed, periodic network health checks should become a part of your routine. As the old saying goes, the only constant is change for most network environments. Consequently, you must constantly reassess your network's ability to satisfactorily handle VOIP traffic and to successfully converge that traffic with traditional data network functions.
Tim graduated from the University of California, Berkeley with degrees in Mathematics, Computer Science and Psychology. Tim taught undergraduate Computer Science at U.C. Berkeley while obtaining a Master's degree in Electrical Engineering and Computer Sciences. He can be reached at firstname.lastname@example.org.