Cisco High-Density Analog Voice and Fax Network Module

Configuration Tasks

Voice Quality Tuning Commands

The commands in this section configure parameters to improve voice quality. Common voice quality issues include the following:

Configuring Adaptive Jitter Adjustment (optional)

Configuring Echo Adjustment (optional)

Configuring Voice Level Adjustment (optional)

Configuring Adaptive Jitter Adjustment

To configure the playout delay jitter buffer, use the following commands beginning in dial-peer or voice-port configuration mode:

 

Command

Purpose

Step 1

 

 

Router(config-voiceport)# playout-delay mode {adaptive

Determines the mode in which the jitter buffer will

 

fixed}

operate for calls on this voice port.

 

 

 

 

The keywords are as follows:

 

 

 

 

adaptive—Adjusts the jitter buffer size and

 

 

 

 

amount of playout delay during a call based on

 

 

 

 

current network conditions.

 

 

 

 

fixed—Defines the jitter buffer size as fixed so

 

 

 

 

that the playout delay does not adjust during a

 

 

 

 

call. A constant playout delay is added.

 

 

 

 

The default is adaptive.

Step 2

 

 

Router(config-voiceport)# playout-delay{nominal value

Tunes the playout buffer to accommodate packet

 

maximum value minimum {default low high}}

jitter caused by switches in the WAN.

 

 

 

 

The keywords and arguments are as follows:

 

 

 

 

nominal—Defines the amount of playout

 

 

 

 

delay applied at the beginning of a call by the

 

 

 

 

jitter buffer in the gateway. In fixed mode, this

 

 

 

 

is also the maximum size of the jitter buffer

 

 

 

 

throughout the call.

 

 

 

 

value—Specifies the range that depends on

 

 

 

 

type of DSP and configured codec complexity.

 

 

 

 

For medium codec complexity, the range is

 

 

 

 

from 0 to 150 ms. For high codec complexity

 

 

 

 

and DSPs that do not support codec

 

 

 

 

complexity, the range is from 0 to 250 ms.

 

 

 

 

maximum (adaptive mode only)—Specifies

 

 

 

 

the jitter buffer's upper limit (80 ms), or the

 

 

 

 

highest value to which the adaptive delay is set.

 

 

 

 

minimum (adaptive mode only)—Specifies

 

 

 

 

the jitter buffer's lower limit (10 ms), or the

 

 

 

 

lowest value to which the adaptive delay is set.

 

 

 

 

default—Specifies 40 ms.

 

 

 

 

 

 

 

 

Cisco IOS Release 12.2(2)XT and 12.2(8)T

 

 

 

 

 

 

 

 

 

 

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Weed Eater 2600 manual Voice Quality Tuning Commands, Configuring Adaptive Jitter Adjustment