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Cisco Unified IP Phone 6921, 6941, and 6961 Administration Guide for Cisco Unified Communications Manager 7.1 (SCCP)
OL-19025-01
Chapter 9 Troubleshooting and Maintenance
General Troubleshooting Tips
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 4-3 for details.
Phone resetting. The phone resets when it loses contact with the Cisco Unified Communications
Manager soft
ware. 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
i
nteracting 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
anot
her 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
v
alues 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 “C
all Statistics Screen” section on page 7-8 for information about
displaying these statistics.
Sound sample mismatch between the
ph
one 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
de
vice. The values of these statistics should match.
See the “C
all Statistics Screen” section on page 7-8 for information about
displaying these statistics.
Gaps in voice calls. Check the AvgJtr and the MaxJtr statistics. A large variance between these
stat
istics might indicate a problem with jitter on the network or periodic high
rates of network activity.
See the “C
all Statistics Screen” section on page 7-8 for information about
displaying these statistics.
Loopback condition. A loopback condition can occur when the following c
onditions 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 (the power supply is disconnected)
In this case, the switch port on the phone
can become disabled and the
following message will appear 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
b
etween phones is not established. Check the configurations in routers and
switches to ensure that IP connectivity is properly configured.
Table 9-1 Cisco Unified IP Phone Troubleshooting (continued)
Summary Explanation