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Cisco IP Phone Administration Guide for Cisco CallManager 3.2, Cisco IP Phones 7960/7940/7910
78-10453-04
Chapter 7 Troubleshooting the Cisco IP Phone
Resolving Known Issues
Step 6 To verify the MAC address on the phone, see the “Verifying Network Settings”
section on page 5-3.
Step 7 Power cycle the phone.
Resolving Known Issues
Refer to the following tables for troubleshooting some common issues that might
occur on you Cisco IP Phones:
• Table 7-2 describes restrictions or other known troubleshooting suggestions
for the Cisco IP Phone models 7960, 7940 and 7910.
• Table 7-3 describes restrictions or other known troubleshooting suggestions
for the Cisco IP Phone 7914 Expansion Module.
Table 7-2 Cisco IP Phone Troubleshooting
Summary Explanation
Daisy-chaining IP phones 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.
Poor quality when calling digital cell
phones using the G.729 protocol
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 cause IP
phones to re-register
Prolonged broadcast storms (lasting several minutes) on the
voice VLAN cause the IP phones to re-register with another
Cisco CallManager server.