Troubleshooting Tips - Cisco 7962G Administration Manual

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

Troubleshooting Tips

When you observe significant and persistent changes to metrics, use
troubleshooting information:
Table 9-5
Metric Change
MOS LQK scores
decrease significantly
MOS LQK scores
decrease significantly
Conceal Ratio and
Conceal Seconds
increase significantly
Conceal Ratio is near or
at zero, but the voice
quality is poor.
Voice quality metrics do not account for noise or distortion, only frame loss.
Note
Cisco Unified IP Phone 7962G and 7942G Administration Guide for Cisco Unified Communications Manager 6.0
9-18
Unlike MOS, the Conceal Ratio and Concealed Seconds metrics remain valid and useful for both
wideband and narrowband calls.
Changes to Voice Quality Metrics
Condition
Network impairment from packet loss or high jitter:
•
•
Cross-check with Conceal Ratio and Conceal
Seconds for evidence of packet loss and jitter.
•
•
•
•
•
•
Check packet transmit (TxCnt) and packet receive
(RxCnt) counters to verify that voice packets are
flowing.
Average MOS LQK decreases could indicate
widespread and uniform impairment.
Individual MOS LQK decreases indicate bursty
impairment.
Check to see if the phone is using a different
codec than expected (RxType and TxType).
Check to see if the MOS LQK version changed
after a firmware upgrade.
Network impairment from packet loss or high
jitter.
Noise or distortion in the audio channel such as
echo or audio levels.
Tandem calls that undergo multiple
encode/decode such as calls to a cellular
network or calling card network.
Acoustic problems coming from a
speakerphone, handsfree cellular phone or
wireless headset.
Chapter 9 Troubleshooting and Maintenance
Table 9-5 for general
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