How to Ensure a Successful VoIP System Implementation

Step #3: Accurately estimate network resource use

Accurately estimate the network resource use for the proposed VoIP system. Unlike traditional land lines where users have the equivalent of dedicated switch ports, a VOIP system is usually placed on a shared medium. Converged networks are what everyone is trying to implement to save money. Be sure to consider the number of simultaneous calls that will occur. With that information in hand, you can easily calculate the aggregate bandwidth that will be needed to support all calls during peak calling periods.

By benchmarking the requirements for a single VoIP call, computing the aggregate call traffic and comparing these values with baselines of existing network activity, it will be simple to determine if VoIP will “fit” in your current network. If the numbers do not add up, you may need to consider architectural changes to your IT infrastructure.

Step #4: Select a codec with higher speech sampling rates

Select a codec with higher speech sampling rates. In general, the higher the speech sampling rate, the better the potential call quality (but at the expense of more bandwidth being consumed). Make tradeoffs carefully. For example, G.711 provides excellent quality. Data is delivered at 64K bps, and the codec imposes no compression delay.

Technically, G.711 delivers 8,000 bytes per second without compression so that full Nyquist-dictated samples are provided. However, if you are attempting to pack multiple phone calls over a narrow bandwidth circuit, you may need to accept slightly lower quality to use a codec that is less hungry for bandwidth.

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 prioritise 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.

Conclusion

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.