VoIP Call Quality Must Equal PSTN

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The Mean Opinion Score (MOS) is the subjective scale by which telephone network end user quality is measured. According to a TechNewsWorld story, providers of traditional network services aim for scores of 3.5 to 4.2 on the five-point scale.


The challenge for VoIP providers is that their scores generally aren't as high, the story says. The implication is that the disparity between traditional and VoIP quality grows as problems not apparent in small-scale VoIP tests and beta projects become issues in enterprise-wide rollouts.


The disparity between traditional and VoIP services is understandable. The legacy public switched telephone network (PSTN) has a headstart of, say, 100 years or so. It is robust, predictable and solid. VoIP networks all have sprung up during the past few years. They are built on a network infrastructure that simply wasn't intended for voice services. Vendors and service providers have done an amazing job of scrambling -- but scambling it is.


This means that the networks aren't going to be perfect. It also means that VoIP is at a crossroads as it fights competitors' high-quality voice services. The current dynamic -- that VoIP is a huge hit and is dominating the deployment of new voice lines -- won't last if VoIP quality trends below that of the PSTN. Companies like to save money and take advantage of all the hyped features VoIP offers. But they are smart enough to recognize that such a strategy is foolish if the quality of the bedrock voice product isn't as good.


VoIP isn't going anywhere. It's already part of too many business and operational plans to fade away. What could happen, however, is that consistent quality problems relegate VoIP to a secondary role in the enterprise. For instance, lines that are used to communicate with customers could be time-division multiplexed (TDM), while intraoffice communications could be VoIP. If such a two-tier scenario develops, it also is likely that enterprises will revisit and perhaps reverse decisions to go with VoIP before deployment begins.


Of course we don't know how this is going to play out. The bottom line, however, is clear: Voice is the most important telecommunications service for every company. If VoIP doesn't create networks robust enough to be the equal of the PSTN and, on top of that, develop the testing, quality control and remediative tools necessary to keep applications running smoothly, its star will begin to fade.