General Troubleshooting Tips For The Cisco Ip Phone - Cisco 7960G Administration Manual

Chapter 8 Troubleshooting the Cisco IP Phone

General Troubleshooting Tips for the Cisco IP Phone

Table 8-2 Cisco IP Phone Troubleshooting
Summary
Daisy-chaining IP phones.
Poor quality when calling digital cell
phones using the G.729 protocol.
Prolonged broadcast storms cause IP
phones to re-register.
Cisco IP Phone Administration Guide for Cisco CallManager 4.0, Cisco IP Phones 7960G/7940G
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Table 8-1 Cisco IP Phone Security Troubleshooting (continued)
Problem
Phone does not interact with the
correct CAPF server to obtain the
locally-significant certificate.
Phone does not request signed
configuration files.
Table 8-2 provides general troubleshooting information for the Cisco IP Phone.
Explanation
Do not connect an IP phone to another IP phone through the
access port. Each IP phone should directly connect to a switch
port. If you connect IP phones together in a line
(daisy-chaining), a problem with one phone can affect all
subsequent phones in the line. Also, all phones on the line share
bandwidth.
In Cisco CallManager, you can configure the network to use the
G.729 protocol (the default is G.711). When using G.729, calls
between an IP phone and a digital cellular phone will have poor
voice quality. Use G.729 only when absolutely necessary.
Prolonged broadcast storms (lasting several minutes) on the
voice VLAN cause the IP phones to re-register with another
Cisco CallManager server.
General Troubleshooting Tips for the Cisco IP Phone
Possible Cause
The CAPF utility runs on a different
•
workstation/server than is specified
in the CTL file.
The CAPF certificate has changed
•
since the last update of the CTL file.
The CTL file does not contain any
•
TFTP server entry.
The CTL file does not contain any
•
TFTP entries with certificates
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