© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Configuring Voice Networks Adjusting Voice Interface Settings

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Outline Overview Factors Affecting Voice Quality Setting Input and Output Power Levels Voice Quality Tuning Echo Cancellation Commands Summary Lesson Self-Check

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Factors Affecting Voice Quality These factors affect voice quality: Transmit and receive power levels Input gain Output attenuation

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Calculating Decibel Levels

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Configuring Voice Port Voice Quality Tuning input-gain output-attenuation impedance

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Configuration Examples

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Echo Cancellation Echo cancellation is configured at the voice port level. Echo cancellation is enabled by default. Echo cancellation coverage adjusts the size of the echo canceller. Nonlinear echo cancellation shuts off any signal if near-end speech is detected.

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Summary Voice quality is affected by the settings on each voice port. Factors that affect voice quality include transmit and receive power levels, input gain, and output attenuation. Input and output power levels must be configured to match the connected devices. If the impedance is set incorrectly (if there is an impedance mismatch), a significant amount of echo is generated. Impedance settings must match the connecting equipment. To eliminate echo on a voice call, you can configure echo cancellation using the echo-cancel enable, echo-cancel coverage, and non-linear commands.

© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v5.02-9