Cisco 7975G Troubleshooting And Maintenance page 17

Troubleshooting and Maintenance
Summary
Changing the telephone configuration
Codec mismatch between the phone and another
device
Sound sample mismatch between the phone and
another device
Gaps in voice calls
Loopback condition
General Troubleshooting Information
Explanation
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 Unlock and Lock Options
for details.
The RxType and the TxType statistics show the codec
that is 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 for information about
displaying these statistics.
The RxSize and the TxSize statistics show the size of
the voice packets that are 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 for information about
displaying these statistics.
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 for information about
displaying these statistics.
A loopback condition can occur when the following
conditions 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.
Troubleshooting and Maintenance
17