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Cisco Unified IP Phone 6901 and 6911 Administration Guide for Cisco Unified Communications Manager 8.5 (SCCP and SIP)
OL-23874-01
Chapter 7 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
“Accessing
the Phone Configuration Settings” section on page 4-2 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.
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.
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.
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.
Loopback condition. 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.
One-way audio. When at least one person in a call does not receive audio, IP connectivity between
phones is not established. Check the configurations in routers and switches to ensure
that IP
connectivity is properly configured.
Phone call cannot be established. The phone does not have a DHCP IP address, is unable to register to Cisco Unified
Communications Manager, and shows a Configuring IP or Registering message.
Verify the following:
1. The Ethernet cable is attached.
2. The Cisco CallManager service is running on the Cisco Unified
Communications Manager server.
3. Both phones are registered to the same Cisco Unified Communications
Manager.
4. Audio server debug and capture logs are enabled for both phones. If needed,
enable Java debug.
Table 7-1 Cisco Unified IP Phone Troubleshooting (continued)
Summary Explanation