Psytechnics algorithms ensure VoIP voice quality

Telecommunications Americas, July-August, 2004 by Jim Barthold

All the cost savings and advanced features associated with VoIP won't be worth the ether on which they're transported if the conversations are unintelligible. With that in mind, Psytechnics, a British Telecom spin-off, has developed an algorithm that automates MOS (mean opinion score) voice quality measurements without human intervention. Called PsyQ, Psytechnics' VoIP network management software considers IP bearer performance as well as what edge device is used to turn the IP stream back into voice, said Mike Hollier, the company's CTO.

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"That's really important, because you can imagine the same network connected to two different edge devices could give two completely different user experiences," Hollier explained. "Psytechnics' VoIP quality assessment algorithm can take account of which edge device is going to convert the packet stream back to voice to make a real accurate prediction of user experience."

The algorithm, which will be sold to test and measurement software providers, network management companies and infrastructure vendors, has been tested with BT, Hollier said, and "that's highlighted some pretty interesting things."

For instance, he said, while there are a number of conventional network alarms indicating problems with packet loss and jitter, "they don't really help you find the fault with the customer's hearing. Our software is able to pinpoint faults that are noticeable to a human being, and the combination of MOS and diagnostics we can produce enable you to service faults very effectively."

In fact, he said, within hours of deploying the software with BT, "we were able to discover the service-affecting fault, get that sorted out and leave them with a pretty happy customer."

Unlike conventional MOS testing, the automated software is ongoing, because "you can't just stick a measurement system on there at 9:00 on a Thursday morning and say everything's fine; you really need a real-time monitor," Hollier said.

Psytechnics doesn't reveal end user prices for the software, because those will depend on the OEM partners and how they will use it. "The intention," he said, "is to make it very cost-effective." The intention, further, is to drive VoIP into the marketplace by assuring voice quality.

"Existing engineering ... quantities are not a good predictor of whether the customer did or did not hear decent voice quality," Hollier said. "The job of the algorithms we produce is really to measure the voice quality."