Specifications

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Cisco Unified IP Phone Administration Guide for Cisco Unified Communications Manager 8.5
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Chapter 9 Troubleshooting and Maintenance
General Troubleshooting Tips
Moving a network connection
from the phone to a workstation
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.
Caution The computer’s network card cannot receive power
through the network 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.
Changing the telephone
configuration
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 Unlocking and Locking
Options, page 4-3 for details.
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) delay
When you are on a call that requires keypad input, if you press the
keys too quickly, some of them might not be recognized.
Codec mismatch between the
phone and another device
The RxType and the TxType statistics show the codec that is being
used for a 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 7-15 for information about
displaying these statistics.
Sound sample mismatch
between the phone and another
device
The RxSize and the TxSize statistics show the size of the voice
packets that are 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 7-15 for 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 7-15 for information about
displaying these statistics.
Table 9-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary Explanation