Deficiencies in physical infrastructure/cabling, switching fabric, routing environment, and service provider networks can render the best IP-PBX on the planet a spectacular failure.

In my day job, I spend a lot of time debating the benefits of open source IP PBX solutions versus their proprietary competitors. There are a lot of options in the IP PBX market today and amongst those there are both good and bad products in both the open source and proprietary vendor segments. Independent of the PBX equipment decision, many aspects of a network impact the success or failure of a VoIP implementation project. Prior to my work at Digium (sponsor of Asterisk and Asterisk SCF), I spent my days building VoIP networks for corporations and carriers, and over my decade in that business I learned a very simple lesson: always put the plumbing first.

By plumbing, I mean the network-layer media, equipment and services that handle everything except making and taking phone calls. This realm includes your physical infrastructure and cabling, your switching fabric, your routing environment and your service provider networks. Deficiencies at any of these layers can render the best IP PBX on the planet a spectacular failure. It is important to remember that when you are building a network to support media, you are building for user experience and this raises the bar for performance and management across your network infrastructure.

Here are a few specific recommendations to consider when you are setting out to deploy media (voice or video) across a network of any size.

Build a Media-Capable LAN
A media-capable LAN is a local network infrastructure that has the ability to prioritize and protect real time media moving within it. In order to achieve this design, a network must have a switching fabric that, at a minimum, supports the prioritization of certain traffic types via differentiated services (diffserv) and the segmentation of networks via VLANs (802.1Q). Real time media should be insulated from the balance of data traffic on your LAN and switched with priority to ensure the highest possible quality, to facilitate troubleshooting and to provide a quality user experience.

Give Media Its Own Route
In the same way that it is important to segment real time media from other traffic inside of your local network, this traffic must also be separately routed and managed at the gateway to your company’s network. If your real time media is consolidated with all of your other traffic traversing your gateway, you have no means of selectively troubleshooting performance issues when they arise. At a bare minimum, you should route real time media at its own IP address, but if you have the right equipment you can route media on its own interface and gain better control for performance and management.

Buy Services Based on Network Analysis
Over the last five years there has been a dramatic increase in the quantity and types of vendors offering bring-your-own-bandwidth VoIP services over the Internet. When selecting a provider for VoIP services, it is important to investigate the quality of connection between your company’s network and the network of your proposed vendor(s). By taking a close look at network performance attributes between you and your provider such as router hops, jitter, latency and voice quality beyond your provider’s network, you can qualify or disqualify potential vendors based upon their performance and save yourself headaches down the road associated with poor voice quality.

Use Good Equipment
It has been my experience that equipment quality can have a significant impact on the perceived performance of a VoIP infrastructure. For example, a cheap headset or handset can cause issues that are easily misinterpreted as network performance concerns. This can send your network admin and your provider into a fruitless support effort that might or might not be successfully traced back to the cheap equipment. The amount of money that can be saved buying cheap equipment pales in comparison to the amount of lost productivity that you can incur trying to troubleshoot and eradicate quality issues for your users. By buying quality equipment, you can take a long list of potential contributors off the list for your support resources and focus on those things most likely to help them address a problem.

This is by no means a comprehensive list of considerations when transitioning to VoIP. There are many factors that come together to dictate the success or failure of a VoIP implementation project. However, these points are the stand-out contributors to VoIP network performance in my years of experience in that business. Just because the technology and the services around it offer the promise of being less expensive to operate that does not mean that you should deploy the least expensive equipment or service options. Do your research, be selective and don't sell yourself short and you'll find that a conversion to VoIP infrastructure and services will pay off to your expectations.