Specifications

9-16
Cisco Unified IP Phone 7906G and 7911G for Cisco Unified Communications Manager 8.0
OL-21033-01
Chapter 9 Troubleshooting and Maintenance
Where to Go for More Troubleshooting Information
Note Voice quality metrics do not account for noise or distortion, only frame loss.
Where to Go for More Troubleshooting Information
If you have additional questions about troubleshooting the Cisco Unified IP Phones, these Cisco.com
web sites can provide you with more tips.
• Cisco Unified IP Phone Troubleshooting Resources:
http://www.cisco.com/en/US/products/hw/phones/ps379/tsd_products_support_series_home.html
• Cisco Products and Services (Technical Support and Documentation):
http://www.cisco.com/en/US/products/sw/voicesw/tsd_products_support_category_home.html
Cleaning the Cisco Unified IP Phone
To clean your Cisco Unified IP phone, use a soft, dry cloth to wipe the phone screen. Do not apply
liquids or powders directly on the phone. As with all non-weather-proof electronics, liquids and powders
can damage the components and cause failures.
Table 9-4 Changes to Voice Quality Metrics
Metric Change Condition
MOS LQK scores
decrease significantly
Network impairment from packet loss or high jitter:
• Average MOS LQK decreases could indicate widespread and uniform impairment.
• Individual MOS LQK decreases indicate bursty impairment.
Cross-check with Conceal Ratio and Conceal Seconds for evidence of packet loss and jitter.
MOS LQK scores
decrease significantly
• 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.
Conceal Ratio and
Conceal Seconds
increase significantly
• Network impairment from packet loss or high jitter.
Conceal Ratio is near
or at zero, but the
voice quality is poor.
• 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.