Test Your Way to VoIP Success 

By Jeff Fried
June 2005

Voice over IP (VoIP) is here to stay.  A recent Empirix survey indicated that 98 percent of enterprises surveyed have already deployed or have plans to deploy VoIP; 2005 will be a year in which the number of new VoIP phones will exceed the number of TDM (Time Division Multiplex) phones shipped to enterprises.  Clearly, the number of VoIP deployments is accelerating.

Like the technology itself, the business benefits of VoIP have evolved over time.  Originally, VoIP projects were justified on the basis of reduced operating costs, either for toll bypass or the lower operating costs of a "single network."  The single biggest justification was "virtualization," the ability to work anywhere and tie geographically dispersed and mobile employees into a single system.  These justifications remain strong, but enterprises have found that the strongest recurring value is in the applications themselves, such as contact centers, messaging, auto-attendants, CTI, and conferencing – traditional applications made more manageable, more cost-effective, and more uniformly available by VoIP (See Figure 1). 

While VoIP can offer tremendous benefits, to deploy the technology successfully, an enterprise must overcome several challenges.  First, because VoIP is an emerging technology, there are evolving standards and competing approaches, which can lead to interoperability issues.  Second, typical characteristics of IP networks – like latency, jitter, and packet loss – can affect voice quality.  Finally, the successful deployment of VoIP often requires new organizational structures and the consolidation of voice and data IT teams.  

In spite of all these challenges, the expectations for VoIP deployments are high: five 9's availability, toll quality, clean interoperability and applications, and dial tone even when the lights go out.  Consistent, comprehensive testing of both the VoIP infrastructure and the applications running on it can enable enterprises to meet these challenges head-on.

Take a Lifecycle Approach to Testing: The vast majority of VoIP deployment issues are avoidable with proper planning, training, processes, and tools.  By viewing deployment as a lifecycle with distinct phases and by being ready for each phase ahead of time, enterprises can ensure smoother rollouts and achieve benefits more fully while saving significant time and money.  A lifecycle approach includes: 

• Baselining the current network via a network assessment

• Testing the network infrastructure multiple times as the network is prepared for VoIP

• Testing vendor solutions during the procurement process

• Testing applications and infrastructure during installation and through cutover 

• Ongoing testing, troubleshooting, and management after the cutover

Keep in mind that while ideally testing occurs early in the process, it is never too late to test.  Many organizations find they need to turn to baselining or network testing mid-project, after they run into problems.

Ensuring Voice Quality: Voice quality is extremely important, especially for contact centers where poor quality can turn away customers and burn out agents.  But voice applications are demanding.  They are very sensitive to packet-level impairments such as packet loss, delay, and jitter – all of which are specific to a given environment and change with traffic load.  At the same time, voice quality depends on these packet-level characteristics, as well as on echo, codec quality, application, and individual users' perceptions.  Quality can vary within a call, and the type, make, and model of "endpoint" (traditional hardphone, soft-phone, PDA, or wireless VoIP phone) can make a huge difference.

Since voice quality is subjective, quality measurement is a key practice for any VoIP deployment.  The state of the art today requires multiple kinds of voice quality measurements, carried out on a periodic basis both before and after deployment.  VoIP-specific testing with voice quality measurement is a critical, often overlooked practice to check a variety of key factors, including:

• Capacity and specific "normal" character of a given environment

• Proper network configuration 

• Detection and resolution of any interoperability issues

• Sensitivity of voice quality to traffic load and infrastructure parameters

Testing at the Application Level: Voice applications such as conferencing, voice mail, call routing, voice self service, teleworking, and click-to-talk are what typically provides value from IP telephony.  They all benefit from another layer of testing, over and above infrastructure testing.

Applications tend to have a number of potential paths and many configuration parameters.  IP telephony applications are no exception, and they have the additional twist that the way they interact with a new infrastructure can change the effectiveness of the application – sometimes dramatically.  Once the VoIP infrastructure is tested and good baseline measurements are captured, application-level testing can be done effectively.  Typical areas to test are:

• Signaling latency (speed of dial tone, speed of call transfer)

• Reliability of application information delivery (screen pops, information elements use for routing)

• Application performance (IVR responsiveness, application performance under load) 

• Impact of VoIP on applications (speech recognition accuracy with packet loss, conference bridge loudest-speaker detection)

• All-paths testing (correct configuration of all forwarding, hunting, routing, voicemail, and messaging configuration)

Be Prepared for Troubleshooting

While proper preparation and testing can help organizations avoid the majority of problems that occur in production, ongoing monitoring, management, and optimization are important as well.  Troubleshooting tools and techniques can speed resolution and minimize the impact of problems that do occur.  Enterprises that plan for this from the start have all their bases covered and will have the best experiences with VoIP deployments.

There are many moving parts to manage in enterprise VoIP deployments, so troubleshooting is especially important.  Most VoIP deployments are multi-site and multi-vendor, so interoperability remains somewhat problematic even after cutover.  Subtle interactions between infrastructure and applications often surface with changes in traffic or configuration.  Many VoIP-related problems are transient in nature and can occur at multiple places in the infrastructure.  For this reason, a skilled troubleshooter needs a variety of tools at his or her disposal.  For example, an analyzer capable of tracing and troubleshooting VoIP at the call level can be indispensable.

Careful planning throughout the entire lifecycle can help enterprises meet the challenges of VoIP deployment before they turn into Quality of Service issues.  The best way to prepare for and combat the quality issues inherent in a converged network is to test the network thoroughly before rollout.  The best way to prepare for VoIP application rollout and troubleshooting is to baseline VoIP applications and then test across a range of conditions to anticipate and resolve problems before they arise in production.  When good tools and processes are used, VoIP deployments can go smoothly and provide great business benefit.

Jeff Fried is CTO of the Enterprise Solutions Group at Empirix Inc.  He can be reached at jfried@empirix.com or 781-266-3200.  Visit Empirix at www.empirix.com.

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