Cisco 7940G Administration Manual page 87

Chapter 7 Troubleshooting and Maintenance
Table 7-2 Cisco Unified IP Phone Troubleshooting (continued)
Summary
Checking the handset cradle clip.
Checking the hook switch contacts.
Checking the position of the phone.
Checking the LAN cable.
Loopback condition.
Cisco Unified IP Phone 7960G/7940G Administration Guide for Cisco Unified Communications Manager 7.0 (SIP)
OL-15499-01
Explanation
Cisco Unified IP Phones are designed with a reversible handset clip in the cradle. This
clip is used with the plastic tab protruding out when the phone is in a vertical
(wall-mounted) position. The position of the tab can interfere with the handset as it is
placed in the cradle. If the phone remains in the on-hook position you may experience
continued ringing when you try to answer a call or a lack of dial tone when you try to
place a call. To resolve this problem, you may need to reverse the clip.
If the handset cradle clip is in the wall-mounted position and your phone is placed on
a desktop, slide the clip upward to remove it. Rotate the clip 180 degrees and slide it
back in so that the tab is hidden.
If the hook switch remains in the down position, tapping on the phone should free up
the switch. You can also try pushing and suddenly releasing the off-hook button after
the handset has been picked up.
The hook switch contacts on the phone use a wiping action to self-clean the contacts.
If your phone is not used regularly, dust and other airborne contaminants may degrade
the contact performance and cause problems with operation. If you have periods of
limited phone usage, you can clean the contacts by quickly pressing and releasing the
hook switch a dozen times.
The footstand of the phone allows adjustment of the phone to eliminate glare on the
LCD screen. When the phone is in the most vertical position, the phone may be forced
forward and the handset may not sit properly in the cradle, creating a false off-hook
condition. Cisco recommends that you position the phone one notch from the most
vertical position to ensure that the handset is firmly resting on the hook switch.
Make sure that the LAN cable connected to the phone is positioned properly. The
LAN cable should pass out of the side of the phone between the base and the
footstand. If you are using a cable (such as Cat-5E or Cat-6) with a larger diameter
than the cable that was packaged with your phone, the cable may cause the phone to
tilt forward and force it off-hook. Use a smaller LAN cable to eliminate this problem.
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 10H
(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.
General Troubleshooting Tips for the Cisco Unified IP Phone
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