Voice Quality

Arptel Telemanagment Platform uses modern algorithms to calculate Voice Quality on intrusive test calls (TCS) or non-intrusive monitored links (Network Monitor).

What is Voice Quality?

Quality is the customer’s perception of a service or product. Voice quality measurement is a means of measuring customer experience of voice telephony services.

How is Voice Quality Measured?

The most accurate way of measuring voice quality would be to interrupt calls and ask users what they think. This is obviously neither practical nor scalable.

Instead, a series of subjective tests was undertaken during which people of all ages and races are played the same series of sound files and asked to rank them on a scale of 1 to 5 for voice quality. From these results, algorithms were developed which are now used to measure voice quality from the customer perspective on this scale of 1 to 5.

The voice quality scores are known as Mean Opinion Scores (MOS) and the scale of 1 to 5 is standardised by the International Telecommunications Union (ITU), the United Nations body responsible for telecommunications standardisation.

Quality scores:
5	Execellent
4	Good
3	Fair
2	Poor
1	Bad

Can You Hear the Difference?

A typical fixed-line network which most people have in their homes has an average MOS of 4.3 and GSM networks average a MOS of between 2.9 and 4.1. If voice quality were to drop by 1 MOS during a call, the average user would clearly hear the difference. A drop of half a MOS is audible whereas a quarter of a MOS is just noticeable.

NIQA

Arptel uses the NIQA algorithm in the TCS system for test calls to far destinations, measuring MOS scores without a reference voice in the far end. This is the only possible solution for testing your foreign destination as it is nearly impossible to have reference voices in all destinations.

NIQA is also used in our non-intrusive Network Monitor system.

PESQ

Arptel uses the PESQ algorithm in the TCS system for test calls to destinations for measuring MOS scores with a reference voice in the far end or with some loop back device. TCS with PESQ can easily verify all your VoIP links on a regular basis and send an alert if the quality is degraded.

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