Cisco 7975G Software Manual page 179

Chapter 9 Troubleshooting and Maintenance
Table 9-2
Summary
Prolonged broadcast storms
cause IP phones to reset, or be
unable to make or answer a call
Moving a network connection
from the phone to a workstation
Changing the telephone
configuration
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
Cisco Unified IP Phone 7975G Administration Guide for Cisco Unified Communications Manager 7.0 (SCCP and SIP)
OL-15790-01
Cisco Unified IP Phone Troubleshooting (continued)
Explanation
A prolonged Layer 2 broadcast storm (lasting several minutes) on
the voice VLAN may cause IP phones to reset, lose an active call,
or be unable to initiate or answer a call. Phones may not come up
until a broadcast storm ends.
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
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
Options" section on page 4-3
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 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 a transcoder is in place to handle the service.
See the
information about displaying these statistics.
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
information about displaying these statistics.
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.
for details.
"Call Statistics Screen" section on page 7-13
"Call Statistics Screen" section on page 7-13
General Troubleshooting Tips
"Unlocking and Locking
for
for
9-11