Monitoring the Voice Quality of Calls

Chapter 9 Troubleshooting and Maintenance

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, and/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, refer to Cisco Unified Communications Manager Features and Services Guide.

To measure the voice quality of calls that are sent and received within the network, Cisco Unified IP Phones use these 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—Show the ratio of concealment frames over total speech frames. An interval conceal ratio is calculated every 3 seconds.

•Concealed Second metrics—Show 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—Use 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.

MOS LQK scores are produced by a Cisco proprietary algorithm, Cisco Voice Transmission Quality (CVTQ) index. 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.

Listening quality scores (MOS LQK) relate to the clarity or sound of the received voice signal. Conversational quality scores (MOS CQ such as G.107) include impairment factors, such as delay, that degrade the natural flow of conversation.

You can access voice quality metrics from the Cisco Unified IP Phone by using the Call Statistics screen (see the “Call Statistics Screen” section on page 7-13) or remotely by using Streaming Statistics (see the “Monitoring the Cisco Unified IP Phone Remotely” chapter).

Using Voice Quality Metrics

To use the metrics for monitoring voice quality, note the typical scores under normal conditions of zero packet loss and use the metrics as a baseline for comparison.

	Cisco Unified IP Phone 7970G/7971G-GE Administration Guide for Cisco Unified Communications Manager 7.0

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7970G, 7971G-GE specifications

The Cisco Systems 7971G-GE is a sophisticated IP phone designed for enterprise communication, offering a range of features that enhance productivity and collaboration. As part of the Cisco Unified Communications portfolio, this phone is known for its impressive technology and reliable performance.

One of the main features of the 7971G-GE is its high-resolution color display. The 5-inch LCD screen provides users with a visually appealing and intuitive interface, allowing for easy navigation through menus and contacts. The phone supports up to six lines, making it ideal for users who require multiple lines for simultaneous calls. Users can effortlessly manage calls with the ability to switch between lines and access important call features like hold, transfer, and conference calling.

In terms of audio quality, the Cisco 7971G-GE is equipped with high-definition voice technology. This feature ensures crystal-clear sound during calls, reducing background noise and enhancing the clarity of conversations. The phone also supports wideband audio codecs, enabling a richer voice experience that is particularly valuable in business environments.

The phone is designed with user convenience in mind. It offers programmable buttons that can be customized to suit individual needs, allowing easy access to frequently used functions or contact lists. Additionally, the presence indicator feature lets users see the availability of their colleagues in real-time, promoting more effective communication and collaboration.

Networking capabilities are another strong point of the Cisco 7971G-GE. The phone supports both Power over Ethernet (PoE) and standard Ethernet connectivity. This enables easy deployment without the need for additional power outlets. Moreover, the device is compatible with various Cisco communication platforms, integrating seamlessly with existing Cisco infrastructure, which is essential for businesses looking to upgrade their communications systems.

Security is a crucial consideration for modern enterprises, and Cisco addresses this with robust encryption features that protect voice and video calls. The phone supports secure signaling and media encryption, ensuring that sensitive conversations remain confidential.

Overall, the Cisco Systems 7971G-GE is a feature-rich IP phone that combines advanced technology with user-friendly design. Its high-definition audio, customizable features, and seamless integration with Cisco networks make it a popular choice for businesses seeking to improve their communication systems. With its reliability and performance, the Cisco 7971G-GE continues to support effective collaboration in an increasingly connected world.

Cisco Systems 7971G-GE, 7970G Monitoring the Voice Quality of Calls, Using Voice Quality Metrics

Models: 7970G 7971G-GE