Cisco 7800 Series Administration Manual page 195

Concealment ratio and concealment seconds are primary measurements based on frame loss. A Conceal
Note
Ratio of zero indicates that the IP network is delivering frames and packets on time with no loss.
You can access voice quality metrics from the Cisco IP Phone using the Call Statistics screen or remotely by
using Streaming Statistics.
Voice Quality Troubleshooting Tips
When you observe significant and persistent changes to metrics, use the following table for general
troubleshooting information.
Table 14: 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
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 7800 Series for Third-Party Call Control Administration Guide
Voice Quality Monitoring
181