Table Of Contents

Troubleshooting

Troubleshooting

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Refer to the following tables for troubleshooting suggestions:

•Table 7-1 describes restrictions or other known troubleshooting suggestions for the Cisco IP Phone models 7960, 7940 and 7910.

•Table 7-2 describes restrictions or other known troubleshooting suggestions for the Cisco IP Phone 7914 Expansion Module.

Table 7-1 Cisco IP Phone Troubleshooting 

Summary	Explanation
Message waiting light does not work with non-Cisco voice mail systems	The message waiting light does not light if you are using a non-Cisco voice mail system, and Cisco CallManager is not configured correctly for that voice mail system. In this case, the user must access the voice mail system to determine if he or she has received new messages.
Messages button does not work with non-Cisco voice mail systems	If you are using a Cisco voice mail system, the messages button retrieves the messages. For non-Cisco voice mail systems, you must access the voice mail system to retrieve messages.
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.
Moving a network connection from the phone to a workstation	If you are powering your phone through the network connection, you must be careful if you decide to unplug the phone's network connection and plug the cable into a desktop computer. The computer's network card cannot receive power through the network connection; if power comes through the connection, the network card can be destroyed. To prevent this, wait 10 seconds or longer after unplugging the cable from the phone. This gives the switch enough time to recognize that there is no longer a phone on the line, and to stop providing power to the cable.
Changing the telephone configuration	To change the telephone configuration, you must press **# and then the Settings button.
Phone resetting	The phone resets when it loses contact with the Cisco CallManager software. This lost connection can be due to any network connectivity disruption, including cable breaks, switch outages, and switch reboots.
LCD display issues	You might see Beat frequencies (scan lines) in the LCD if you are using certain types of old fluorescent lights in your building. Moving the phone away from the lights, or replacing the lights, should resolve the problem.
Dual-Tone Multi-Frequency (DTMF) delay	When you are on a call that requires keypad input, if you press the keys too quickly, some of them might not be recognized.

Refer to the following table if you are having difficulty using your 7914 Expansion Module.

Table 7-2 Expansion Module Troubleshooting

Problem	Solution
No display on the 7914 Expansion Module	Verify that all of the cable connections are correct. Verify that you have power to the Expansion Module(s).
Lighted buttons on the first 7914 Expansion Module are all red.	Verify with your system administrator that your 7914 Expansion Module is defined in Cisco CallManager.
Lighted buttons on the second 7914 Expansion Module are all amber.	Verify with your system administrator that your 7914 Expansion Module is defined in Cisco CallManager.