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Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.5 (SIP)
OL-20861-01
Chapter 12 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 the
“Unlocking and Locking Options” section on page 7-3 for details.
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.
Phone 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 the “Call Statistics Screen” section on page 10-11 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 the “Call Statistics Screen” section on page 10-11 for information about
displaying these statistics.
Gaps or delays 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 the “Call Statistics Screen” section on page 10-11 for information about
displaying these statistics.
Table 12-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary Explanation