User's Manual

Cisco High-Density Analog Voice and Fax Network Module

Configuration Tasks

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

Voice Port Testing Commands

These commands allow you to force voice ports into specific states for testing. They require the use of

Cisco IOS Release 12.0(7)XK or 12.1(2)T or a later release, and they apply to Cisco 2600 series,

Cisco 3640, and Cisco 3660 routers. The following types of voice-port tests are covered:

• Detector-Related Function Tests (optional)

• Loopback Function Tests (optional)

• Tone Injection Tests (optional)

• Relay-Related Function Tests (optional)

• Fax/Voice Mode Tests (optional)

Jerky or choppy speech Variable delay, or jitter, is being introduced by congestion in the

packet network. Two possible remedies are to:

• Reduce the amount of congestion in your packet network.

Pings between VoIP endpoints will give an idea of the

round-trip delay of a link, which should never exceed 300 ms.

Also examine network queuing and dropped packets.

• Increase the size of the jitter buffer with the playout-delay

command. (See the “Configuring Adaptive Jitter Adjustment”

section on page 20.)

Clipped or fuzzy speech Reduce input gain. (See the “Configuring Voice Level

Adjustment” section on page 21.)

Clipped speech Reduce the input level at the listener’s router. (See the

“Configuring Voice Level Adjustment” section on page 21.)

Volume too low or missed DTMF Increase speaker’s output level or listener’s input level. (See the

“Configuring Voice Level Adjustment” section on page 21.)

Echo interval is greater than 25 ms

(sounds like a separate voice)

Configure the echo-cancel enable command and increase the

value for the echo-cancel coverage keyword. (See the

“Configuring Echo Adjustment” section on page 21.)

Too much echo Reduce the output level at the speaker’s voice port. (See the

“Configuring Voice Level Adjustment” section on page 21.)

Table 4 Troubleshooting Voice Port Configurations (continued)

Problem Suggested Action