IP TELEPHONY SERVICES

IP NETWORK SYSTEMS

IP telephony provides a way for you to extend consistent communications services to all your employees in their workspaces, whether they are in main campus locations, at branch offices, working remotely, or are mobile. IP telephony transmits voice communications over the network using open-standards-based Internet Protocol.

IP telephony solutions are an integral part of Unified Communications, which unify voice, video, data, and mobile applications on fixed and mobile networks enabling users to easily communicate in any workspace using any media, device, or operating system.

Using the network as the platform, IP telephony solutions help organisations of all sizes realise greater security, resilience, and scalability in addition to the inherent benefits of using a converged network for transport and interconnection.

An IP telephony audit should be performed for every proposed LAN/WAN segment before the addition of IP telephony traffic. The key to designing an IP telephony network is an understanding of the underlying technology used to transport the IP telephony traffic. The design principles used to deploy a successful LAN based VoIP network will not necessarily work when you apply them to a WAN configuration, due to a number of factors including limited bandwidth. QoS and traffic isolation are the key factors for the LAN, but bandwidth, priority, and delay are important to the WAN. This can make a significant impact on the installation.

One of the most important recommendations that can be made is to pay close attention to the infrastructure that the VoIP network is built on. The foundation must be solid otherwise there will be ongoing quality issues until the network design issues are resolved. The more time spent upfront investigating and verifying the design of the LAN and/or WAN will make a more successful ending. Verification is critical, and although it may seem reasonable to believe that the "network is new and should support QoS," it’s important to check. In some cases, like running VoIP over a WAN, an audit is mandatory. For example, the total end-to-end delay to support a quality voice conversation must not exceed 200 ms and can only be verified by an IP audit. Remember, the longer the delay the worse the quality.

As in most architectures, the more redundancy and availability options designed into the network the better the odds are for a successful installation. The designer must also understand that engineering all of the redundancy options available into the system could adversely affect the performance of the network. For example, adding IP redundancy into the network could increase the jitter because the VoIP packets might take multiple paths to reach the end point. This is not a major concern, but it must be evaluated before deploying the VoIP network.

Redundancy features cost real money, so the main task of the design engineer is to make sure the product meets the customer’s requirements and at the same time keeps the proposal price competitive. In some cases, this could be the difference between winning and losing the opportunity.