Using Voice Quality Metrics - Cisco 7961G - IP Phone VoIP Administration Manual

Monitoring the Voice Quality of Calls
Note

Using Voice Quality Metrics

Cisco Unified IP Phone 7961G/7961G-GE and 7941G/7941G-GE Administration Guide for Cisco Unified CallManager
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MOS LQK scores are produced by a Cisco proprietary algorithm, Cisco
Voice Transmission Quality (CVTQ) index. Depending on the MOS LQK
version number, these scores might be compliant with the International
Telecommunications Union (ITU) standard P.564. This standard defines
evaluation methods and performance accuracy targets that predict listening
quality scores based on observation of actual network impairment.
Concealment ratio and concealment seconds are primary measurements based on
frame loss while MOS LQK scores project a "human-weighted" version of the
same information on a scale from 5 (excellent) to 1 (bad) for measuring listening
quality.
Listening quality scores (MOS LQK) relate to the clarity or sound of the received
voice signal. Conversational quality scores (MOS CQ such as G.107) include
impairment factors, such as delay, that degrade the natural flow of conversation.
For information about configuring voice quality metrics for phones, refer to the
"Phone Features" section in the "Cisco Unified IP Phone" chapter in the Cisco
Unified CallManager System Guide.
You can access voice quality metrics from the Cisco Unified IP Phone by using
the Call Statistics screen (see the
or remotely by using Streaming Statistics (see
Unified IP Phone Remotely").
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.
Chapter 9 Troubleshooting and Maintenance
"Call Statistics Screen" section on page
Chapter 8, "Monitoring the Cisco
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