Chapter 9 Troubleshooting and Maintenance

General Troubleshooting Tips

Table 9-2

Cisco Unified IP Phone Troubleshooting (continued)

 

 

 

Summary

 

Explanation

 

 

 

Phone resetting

 

The phone resets when it loses contact with the Cisco Unified Communications

 

 

Manager software. This lost connection can be due to any network connectivity

 

 

disruption, including cable breaks, switch outages, and switch reboots.

 

 

LCD display issues

If the display appears to have rolling lines or a wavy pattern, it might be

 

 

interacting with certain types of older fluorescent lights in the building.

 

 

Moving the phone away from the lights, or replacing the lights, should resolve

 

 

the problem.

 

 

Dual-Tone Multi-Frequency (DTMF)

When you are on a call that requires keypad input, if you press the keys too

delay

 

quickly, some of them might not be recognized.

 

 

Codec mismatch between the phone and

The RxType and the TxType statistics show the codec that is being used for a

another device

 

conversation between this Cisco Unified IP phone and the other device. The

 

 

values of these statistics should match. If they do not, verify that the other

 

 

device can handle the codec conversation, or that a transcoder is in place to

 

 

handle the service.

 

 

See Call Statistics Screen, page 8-14for information about displaying these

 

 

statistics.

 

 

Sound sample mismatch between the

The RxSize and the TxSize statistics show the size of the voice packets that are

phone and another device

being used in a conversation between this Cisco Unified IP phone and the other

 

 

device. The values of these statistics should match.

 

 

See Call Statistics Screen, page 8-14for information about displaying these

 

 

statistics.

 

 

Gaps in voice calls

Check the AvgJtr and the MaxJtr statistics. A large variance between these

 

 

statistics might indicate a problem with jitter on the network or periodic high

 

 

rates of network activity.

 

 

See Call Statistics Screen, page 8-14for information about displaying these

 

 

statistics.

 

 

Loopback condition

A loopback condition can occur when the following conditions are met:

 

 

The SW Port Configuration option in the Network Configuration menu on

 

 

the phone is set to 10 Half (10-BaseT / half duplex)

 

 

The phone receives power from an external power supply

 

 

The phone is powered down or the power supply is disconnected

 

 

In this case, the switch port on the phone can become disabled and the

 

 

following message appears in the switch console log:

 

 

HALF_DUX_COLLISION_EXCEED_THRESHOLD

 

 

To resolve this problem, re-enable the port from the switch.

 

 

 

One-way audio

 

When at least one person in a call does not receive audio, IP connectivity

 

 

between phones is not established. Check the configurations in routers and

 

 

switches to ensure that IP connectivity is properly configured.

 

 

 

 

 

Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.6 (SCCP and SIP)

 

 

 

 

 

 

OL-23091-01

 

 

9-11

 

 

 

 

 

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Cisco Systems 8.6 manual Summary Explanation, Halfduxcollisionexceedthreshold