Additional Troubleshooting Information; Maintenance - Cisco 3905 Administration Manual

Troubleshooting and Maintenance
Summary
Loopback condition.

Additional Troubleshooting Information

If you have additional questions about troubleshooting the Cisco Unified IP Phones, several Cisco.com web
sites can provide you with more tips. Choose from the sites available for your access level.
• Cisco Unified IP Phone Troubleshooting Resources:
• Cisco Products and Services (Technical Support and Documentation):

Maintenance

The following sections describe phone maintenance.
•
•
•
•
http://www.cisco.com/en/US/products/hw/phones/ps379/tsd_products_support_troubleshoot_and_
alerts.html
http://www.cisco.com/en/US/products/ps10326/tsd_products_support_series_home.html
Cisco Unified IP Phone Reset or Restore, on page 92
Voice Quality Monitoring, on page 93
Voice Quality Metrics, on page 93
Cisco Unified IP Phone Cleaning, on page 95
Cisco Unified SIP Phone 3905 Administration Guide for Cisco Unified Communications Manager 8.6 (SIP)
Additional Troubleshooting Information
Explanation
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.
91