Cisco 7931G Administration Manual page 177

Chapter 9 Troubleshooting and Maintenance
Table 9-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary
Gaps in voice calls
Loopback condition
One-way audio
Peer to peer image distribution fails
Phone call cannot be established
Cisco Unified IP Phone 7931G Administration Guide for Cisco Unified Communications Manager 8.0 (SCCP and SIP)
OL-20798-01
Explanation
Check the AvgJtr and the MaxJtr statistics. A large variance between these statistics
may indicate a problem with jitter on the network or periodic high rates of
network activity.
For information about displaying these statistics, see
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 appears in the switch console log:
HALF_DUX_COLLISION_EXCEED_THRESHOLD
To resolve this problem, re-enable the port from the switch.
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 configures.
If the peer to peer image distribution fails, the phone defaults to using the TFTP server
to download firmware. Access the log messages stored on the remote logging machine
to help debug the peer to peer image distribution feature.
Note These log messages are different than the log messages that are sent to the
phone log.
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:
• The Ethernet cable is attached.
• The Cisco CallManager service is running on the Cisco Unified Communications
Manager server.
• Both phones are registered to the same Cisco Unified Communications Manager.
• Audio server debug and capture logs are enabled for both phones. If needed,
enable Java debug.
General Troubleshooting Tips
Call Statistics Screen, page 7-12.
9-11