Mobile voice quality poor in 39% of calls
Rick Nelson, Editor in Chief -- Test & Measurement World, 4/1/2008
Unsatisfactory voice quality caused more than 66,583,174 mobile subscribers to leave their service provider during 2007, ultimately costing the global mobile services industry approximately $23.6 billion, according to estimates in a September 2007 report from communications-equipment vendor Ditech Networks. A follow-up audit report released February 6 suggests the situation may be even worse, reported Ken Croley, Ditech’s director of marketing. To develop that report, Ditech used its EXi technology to evaluate 630 million live mobile calls in 16 different networks across 12 countries; 39% of calls failed to meet a minimum quality standard set by the ITU.
| See audit highlights, Ditech Networks' audit report, and a white paper on the limitations of PESQ. |
“What our audit shows is that the cost of churn is probably higher than what we estimated back in September, because percentage of calls affected by ambient noise and echo is larger than what’s been previously indicated in the industry,” said Croley, adding that the audit focused on identifying problems—such as ambient noise and acoustic echo—that exist outside of a carrier’s network.
Croley said the audit is unique in providing carriers with quantitative voice-quality data. “Carriers have lots of technology to measure what’s going on inside their network,” he said, “but until now there hasn’t been a technology that will quantify voice quality outside the network. What carriers have not known about is what’s going on with a live subscriber.” EXi, he said, is a complement to the ITU’s Perceptual Evaluation of Speech Quality (PESQ) algorithm, which, he added, does not work well for quality problems that occur outside a network.
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