Cisco 7961G Solución de problemas y mantenimiento - Página 24

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Voice Quality Metric Interpretation

To use the metrics for monitoring voice quality, note the typical scores under normal conditions of zero packet

loss and use the metrics as a baseline for comparison.

It is important to distinguish significant changes from random changes in metrics. Significant changes are

scores that change about 0.2 MOS or greater and persist in calls that last longer than 30 seconds. Conceal

Ratio changes should indicate greater than 3 percent frame loss.

MOS LQK scores can vary based on the codec that the Cisco Unified IP Phone uses.

The following codecs on the Cisco Unified IP Phones 7962G and 7942G provide these maximum MOS LQK

scores under normal conditions with zero frame loss:

• G.711 gives 4.5

• G.722 gives 4.5

• G.728/iLBC gives 3.9

• G.729 A/AB gives 3.8

The following codecs on the Cisco Unified IP Phones 7961G/G-GE and 7941G/G-GE provide these maximum

MOS LQK scores under normal conditions with zero frame loss:

• G.711 codec gives 4.5 score

• G.729A/ AB gives 3.7

Note

• CVTQ does not support wideband (7 kHz) speech codecs, because ITU has not defined the extension of

• Reporting G.711-scale MOS scores for wideband calls through the use of CVTQ allows basic quality

• Unlike MOS, the Conceal Ratio and Concealed Seconds metrics remain valid and useful for both wideband

A Conceal Ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.

When you observe significant and persistent changes to metrics, use the following table for general

troubleshooting information:

Troubleshooting and Maintenance

Remote Monitoring

the technique to wideband. Therefore, MOS scores that correspond to G.711 performance are reported

for G.722 calls to allow basic quality monitoring, rather than not reporting an MOS score.

classifications to be indicated as good/normal or bad/abnormal. Calls with high scores (approximately

4.5) indicate high quality/low packet loss, and lower scores (approximately 3.5) indicate low quality/high

packet loss.

and narrowband calls.

Troubleshooting and Maintenance