Voice Quality Troubleshooting Tips - Cisco 8800 Series Administration Manual

Voice Quality Troubleshooting Tips

When you observe significant and persistent changes to metrics, use the following table for general
troubleshooting information.
Table 50: Changes to Voice Quality Metrics
Metric change
Conceal Ratio and Conceal Seconds
increase significantly
Conceal Ratio is near or at zero, but
the voice quality is poor.
MOS LQK scores decrease
significantly
MOS LQK scores increase
significantly
Voice quality metrics do not account for noise or distortion, only frame loss.
Note
Condition
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.
Check packet transmit (TxCnt) and packet receive (RxCnt) counters
to verify that voice packets are flowing.
Network impairment from packet loss or high jitter levels:
• Average MOS LQK decreases may indicate widespread and
uniform impairment.
• Individual MOS LQK decreases may indicate bursty impairment.
Cross-check the conceal ratio and conceal seconds for evidence of
packet loss and jitter.
• 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.
Cisco IP Phone 8800 Series Administration Guide for Cisco Unified Communications Manager
Voice Quality Monitoring
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