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Cisco IP Phone Administration Guide for Cisco CallManager 3.3, Cisco IP Phones 7902G/7905G/7912G
OL-6313-01
Chapter 6 Troubleshooting the Cisco IP Phone
Resolving Startup Problems
To determine whether the phone is functional, you must eliminate any other
potential problems, such as faulty cables, network outages, lack of power, and so
on. Follow these suggestions to systematically eliminate these other causes.
Procedure
Step 1 To verify that the network port is functional:
a. Exchange the Ethernet cables with cables you know are functional.
b. Disconnect a functioning Cisco IP Phone from another port and connect it to
this network port to verify the port is active.
c. Connect the Cisco IP Phone that will not start up to a different network port
that you know to be good.
d. Connect the Cisco IP Phone that will not start up directly to the port on the
switch, eliminating the patch panel connection in the office.
Step 2 To verify that the phone is receiving power:
a. Verify that the electrical outlet is functional.
b. If you are using in-line power, use the external power supply instead.
c. If you are using the external power supply, switch with a unit you know to be
functional.
Step 3 Cisco IP Phone models 7905G/7912G only. If, after attempting these solutions,
the LCD screen persists in not displaying any characters for at least five minutes,
contact a Cisco technical support representative for additional assistance.
Symptom: Cisco IP Phone Not Registering with
Cisco CallManager
If a phone proceeds past the first stage (LED buttons flashing on and off), and, on
a Cisco IP Phone model 7905G/7912G, continues to cycle through the messages
displaying on the LCD screen, then the phone is not starting up properly. The
phone cannot successfully start up unless it is connected to the Ethernet network
and it has registered with a Cisco CallManager server.