User's Manual

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Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.6 (SCCP and SIP)
OL-23091-01
Chapter 9 Troubleshooting and Maintenance
Using the Quality Report Tool
You can press a key twice in a row, but if you press the keys out of sequence, the factory reset will not
take place.
After you press these keys, the line buttons on the phone flash red, and the phone goes through the
factory reset process.
Do not power down the phone until it completes the factory reset process, and the main screen appears.
Using the Quality Report Tool
The Quality Report Tool (QRT) is a voice quality and general problem-reporting tool for the Cisco
Unified IP Phone. The QRT feature is installed as part of the Cisco
Unified Communications Manager
installation.
You can configure users’ Cisco Unified IP Phones with QRT. When you do so, users can report problems
with phone calls by pressing the QRT softkey. This softkey is available only when the Cisco
Unified
IP Phone is in the Connected, Connected Conference, Connected Transfer, or OnHook states.
When a user presses the QRT softkey, a list of problem categories appears. The user selects the
appropriate problem category, and this feedback is logged in an XML file. Actual information logged
depends on the user selection, and whether the destination device is a Cisco
Unified IP Phone.
For more information about using QRT, see Cisco Unified Communications Manager Features and
Services Guide.
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 the following 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—Shows the ratio of concealment frames over total speech frames. The
phone calculates an interval conceal ratio every 3 seconds.
• Concealed Second metrics—Shows 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—Uses 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.
The phone uses the Cisco proprietary algorithm, Cisco Voice Transmission Quality (CVTQ) index,
to produce MOS LQK scores. Depending on the MOS LQK version number, these scores might be
compliant with the International Telecommunications Union (ITU) standard P.564. This standard
defines evaluation methods and performance accuracy targets that predict listening quality scores
based on observation of actual network impairment.
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.