Deploying IP Voice (VoIP) is a big, important project for most organizations, involving a significant investment in new equipment, cost-justified on promises of increased flexibility and lower cost of operations. But such returns can remain elusive – particular for those who don’t take the time to understand how VoIP works and the ways in which the IT organization, and in particular the networking team, must prepare to ensure acceptable VoIP quality and performance.
The typical story that I’ve heard in dialogues with IT pros goes something like the following. VoIP technology is brought into the lab for testing and works very well. A pilot is rolled out and despite a few snafus, is also generally successful. Production rollout goes ahead, and troubles begin to snowball. Dropped calls, poor call quality, frustrated users, and many, many hours spent trying to figure out what went wrong.
As it turns out, the old maxim “an ounce of prevention is worth a pound of cure” applies here. For VoIP, an ounce of prevention in the form of a network readiness assessment can save many pounds of support effort down the road.
First, a quick word on how VoIP works from the network perspective (and why it sometimes doesn’t) will be helpful here. VoIP uses a unique set of network protocols – some for setting up calls, such as SIP or SCCP, and others for the actual call session, such as RTP. VoIP success can be stymied if any of those protocols are not properly transmitted between call initiator, call server, and ultimately call receiver. During a call, VoIP call quality can suffer from three issues related to the network – packet loss, high latency, or high jitter (packet delivery disorder). All three of those conditions can arise for a number of reasons, but most commonly result from simple network congestion.
With those thoughts in mind, we can plan our ounce of prevention! Assessing VoIP readiness starts with establishing visibility and taking inventory. Visibility is key, because before you can make sure your network is ready for VoIP, you first need to understand what is on your network and how your network is working. Things that you should look for at this stage include:
– Applications that are most active in the network: Pay particular attention to those that are using large amounts of bandwidth on a sustained basis, such as streaming audio or video, big file transfers, and data backups.
– Areas of high utilization: Congestion is the enemy of voice quality, so it’s essential to recognize where VoIP might be choked out. Start with WAN links, where bandwidth is usually already constrained, but don’t forget to assess the LAN as well, which can have congestion issues of its own.
– Presence of any existing IP-based voice or video traffic: You may have VoIP on your network and not even be aware of it! For instance, Skype and Google Voice are present on many networks – particular those that allow BYOD – and Microsoft Lync is often present as well since it is now a bundled option in MS Office suites as well as MS cloud and web-based offerings. Recognizing these products is important in understanding and planning the user side of the rollout, while also helping to reveal how the network is currently handling VoIP traffic.
A very helpful approach to gauging readiness is to set up test VoIP traffic generators to generate synthetic simulated calls from various points in the network. This capability is available within the IP SLA feature set offered by Cisco networking gear, or can be accomplished using test software agents or handheld test devices. First off, this solves the protocol deliverability question, ensuring that VoIP control and session packets can indeed get from point A to point B. Test sessions are then measured for quality, commonly using a combined metric known as Mean Opinion Score (MOS), which takes into account loss, latency, and jitter. MOS scores of 4-5 are good, 3-4 is marginal, and anything less than 3 will be poor quality and unacceptable to most callers.
Finally, and importantly, optimizing the network for long term VoIP success will almost certainly require the use of network Quality of Service (QoS) policies, which are used to mark specific types of traffic for high priority delivery by the network. Typically, VoIP is assigned to a higher priority than, for instance, backup traffic or non-business web browsing, helping to assure that VoIP packets get processed more quickly, resulting in less drops, less latency, and less jitter. A further step can be taken by reserving a specific portion of network bandwidth exclusively for high priority traffic such as VoIP and IP videoconferencing. While these steps will come later in the process, understanding existing network QoS settings, if any, and how well those policies are being complied with across the network are essential as part of the readiness assessment.
So –how do you get started? To start, you will need some specialized tools and training. You can try to make do with the tools you have, or you can buy/install/learn new tools. That won’t be a quick process, but if you choose that route, you will be ready for whatever comes down the road. Another option, and one that many shops choose, is to hire the expertise from an external services provider. This approach removes the learning curve barrier and avoids one-time tools purchases.
While there are lots of helping hands out there, it’s important to realize that because VoIP is a complex issue, you may not want to solely rely upon your VoIP or network products supplier, as they may not fully grasp or respect the bigger picture that is your overall IT environment. For many, a better choice is to engage an independent third party services partner that is fully versed across both categories.
An example of such a services partner is Edgeworx, who offers the EDGE VoIP Readiness Assessment service.* The EDGE service includes network analysis, network design evaluation, and network configuration optimization in support of fully preparing the network for VoIP success. There are other services partners out there too, of course, and if you go this route you will want to make sure that the partners you consider can fill all the gaps that you might have from a resource, expertise, and action perspective.
Whether you choose to take on a VoIP readiness assessment on your own, bring in a partner, or some combination thereof, be prepared for another pleasant surprise. The optimization and configuration measures taken as a result will also improve overall network performance and resilience, meaning that other applications will perform better as well. So in the end, this ounce of prevention may actually be worth more than a pound of cure.
*Note: This post inspired and sponsored by Edgeworx