Cisco 7940G Administration Manual page 86

General Troubleshooting Tips for the Cisco Unified IP Phone
Table 7-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary
Moving a network connection from
the phone to a workstation.
Changing the telephone
configuration.
Phone resetting.
LCD display issues.
Dual-Tone Multi-Frequency (DTMF)
delay.
Codec mismatch between the phone
and another device.
Sound sample mismatch between the
phone and another device.
Gaps in voice calls.
Checking signaling.
Cisco Unified IP Phone 7960G/7940G Administration Guide for Cisco Unified Communications Manager 7.0 (SIP)
7-10
Explanation
If you are powering your phone through the network connection, you must be careful
if you decide to unplug the phone's network connection and plug the cable into a
desktop computer.
The computer's network card cannot receive power through the network
Caution
connection; if power comes through the connection, the network card can
be destroyed. To protect a network card, wait 10 seconds or longer after
unplugging the cable from the phone before plugging it into a computer.
This delay gives the switch enough time to recognize that there is no longer
a phone on the line and to stop providing power to the cable.
By default, the network configuration options are locked to prevent users from making
changes that could impact their network connectivity. You must unlock the network
configuration options before you can configure them. See the
Locking Options" section on page 4-2
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.
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.
When you are on a call that requires keypad input, if you press the keys too quickly,
some of them might not be recognized.
The RxType and the TxType that is being used for a conversation between this IP
phone and the other device 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.
The size of the voice packets that are being used in a conversation between this IP
phone and the other device should match.
Can be caused by a problem with jitter on the network or periodic high rates of
network activity.
To check that signaling is working properly between the phone and
Cisco Unified Communications Manager, press the Speaker button on the phone to
answer a call. If you can answer a call and if you hear a dial tone, signaling is working
properly.
Chapter 7 Troubleshooting and Maintenance
"Unlocking and
for details.
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