Don't ignore voice quality.

One of the major stumbling blocks that still affects many voice-over-IP (VoIP)services today is the quality of the call. Often, it is noticeably inferior to legacy phone systems, and rarely is it better. So the challenge is how to convince the board, or the CFO, that switching to VoIP is a good idea. What makes a phone call of poor quality according to customers?

It can be a single technical fault or a number of impairments that combine to degrade the overall customer experience. Typical problems can be: background noise, echo, delay, clipping, coding errors and mismatches in volume level. In VoIP, there are additional, unique sources of degradation, including packet loss, jitter and latency.

Understanding the voice quality or "customer experience" is a logical starting point for any commercial decision regarding VoIP implementation. If the customer experience is defined as "good," then the quality is good despite what technical statistics may indicate.

Even a small influence from noise, echo or delay could combine to be an atrocious listening experience, although, individually, all of these metrics may be within a set tolerance. Decision makers now can use voice quality measurement (VQM) to help make buying decisions regarding VoIP. VQM algorithms have been developed that "listen" and perceive the overall voice quality in the same way customers do.

The main advantage of VQM is the ability to make business decisions--from both a customer viewpoint and an engineering viewpoint-regarding VoIP implementation, upgrades, service-level agreement (SLA) management and troubleshooting. Voice quality measurement also benefits the maintenance processes and deployment of technical labor, and can help identify quality problems that are going unreported.

Armed with this VQM information, network managers can understand overall network performance and pinpoint impairments that actually affect the way in which customers perceive the voice quality. VoIP networks can be implemented and managed with a direct understanding of customer satisfaction.

Financial institutions, with extensive data networks in place, often have been early adopters for converged networks using VoIP. Maintaining excellent, PSTN-levels of voice quality is a key pre-requisite.

In one such example, a bank made a decision to move to an integrated voice and data IP network across 800 branches. One of the key drivers was reducing communications costs; the other, assisting the introduction of new applications to deliver better customer service.

A service provider was awarded the contract to install and manage a consolidated companywide integrated voice and data telecommunication solution. As part of the agreed risk-management strategy, the provider offered various SLA terms and one of these was voice quality on the mean opinion score (MOS).

MOS is the official five-point scale for listening-only tests, including VoIP, which ranges from 1-5, with five being "excellent." AMOS rating of 4.0 is generally considered "toll quality." The contract agreed the voice quality would achieve a MOS of 3.7 or higher, with the service provider trying to consistently deliver a MOS of 3.92.

Network management in terms of MOS was uncharted territory and so the terms of the contract did not specify how MOS would be calculated. The bank requested a third party voice-quality measurement software be integrated into the VoIP system. The results showed that the bank's average MOS score for VoIP calls was at 3.92, close to the customary 4.1.

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This article was provided by Justin Van Der Lande, vice president of Psytechnics, Westford, Mass.