Name: Cisco 7906G
Brand: Cisco
Rating: 4 (1 reviews)

To Next Page

To Previous Page

9-21

Cisco Unified IP Phone 7906G and 7911G Administration Guide for Cisco Unified CallManager 5.1

OL-11515-01

Chapter 9 Troubleshooting and Maintenance

Monitoring the Voice Quality of Calls

To measure the voice quality of calls that are sent and received within the network,

Cisco

Unified IP Phones use these statistical metrics that are based on

concealment events. The DSP plays concealment frames to mask frame loss in the

voice packet stream.

• Concealment Ratio metrics—Show the ratio of concealment frames over total

speech frames. An interval conceal ratio is calculated every 3 seconds.

• Concealed Second metrics—Show the number of seconds in which the DSP

plays concealment frames due to lost frames. A severely “concealed second”

is a second in which the DSP plays more than five percent concealment

frames.

• MOS-LQK metrics—Use a numeric score to estimate the relative voice

listening quality. The Cisco

Unified IP Phone calculates the mean opinion

score (MOS) for listening quality (LQK) based audible concealment events

due to frame loss in the preceding 8 seconds, and includes perceptual

weighting factors such as codec type and frame size.

MOS LQK scores are produced by a Cisco proprietary algorithm (K-factor)

that is an implementation of P.VTQ, an ITU preliminary standard.

Note 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.

You can access voice quality metrics from the Cisco Unified IP Phone by using

the Call Statistics screen (see the

“Call Statistics Screen” section on page 7-18)

or remotely by using Streaming Statistics (see Chapter 8, “Monitoring the

Cisco 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.

Cisco 7906G Administration Guide

Other manuals for Cisco 7906G