Cisco Systems 7960G, 7940G manual General Troubleshooting Tips, Summary Explanation

Chapter 8 Troubleshooting and Maintenance

General Troubleshooting Tips

General Troubleshooting Tips

Table 8-2provides general troubleshooting information for the Cisco Unified IP Phone.

Table 8-2	Cisco Unified IP Phone Troubleshooting
Summary		Explanation
Connecting a Cisco Unified IP Phone		Cisco does not support connecting an IP phone to another IP phone through the PC
to another Cisco Unified IP Phone/		port. Each IP phone should directly connect to a switch port. If phones are connected
		together in a line (by using the PC port), the phones will not work.
Poor quality when calling digital		In Cisco Unified Communications Manager, you can configure the network to use the
mobile phones using the G.729		G.729 protocol (the default is G.711). When using G.729, calls between an IP phone
protocol.		and a digital mobile phone will have poor voice quality. Use G.729 only when
		absolutely necessary.
Prolonged broadcast storms cause		Prolonged broadcast storms (lasting several minutes) on the voice VLAN cause the IP
IP phones to re-register.		phones to re-register with another Cisco Unified Communications Manager server.
Moving a network connection from		If you are powering your phone through the network connection, you must be careful
the phone to a workstation.		if you decide to unplug the phone’s network connection and plug the cable into a
		desktop computer.
		Caution 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 protect a network card, wait 10 seconds or longer after
			unplugging the cable from the phone before plugging it into a computer.
			This delay 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		By default, the network configuration options are locked to prevent users from making
configuration.		changes that could impact their network connectivity. You must unlock the network
		configuration options before you can configure them. See the “Unlocking and Locking
		Options” section on page 4-2for details.
Phone resetting.		The phone resets when it loses contact with the Cisco Unified Communications
		Manager software. This lost connection can be due to any network connectivity
		disruption, including cable breaks, switch outages, and switch reboots.
LCD display issues.		If the display appears to have rolling lines or a wavy pattern, it might be interacting
		with certain types of older fluorescent lights in the building. Moving the phone away
		from the lights, or replacing the lights, should resolve the problem.
Dual-Tone Multi-Frequency (DTMF)		When you are on a call that requires keypad input, if you press the keys too quickly,
delay.		some of them might not be recognized.
Codec mismatch between the phone		The RxType and the TxType statistics show the codec that is being used for a
and another device.		conversation between this IP phone and the other device. The values of these statistics
		should match. If they do not, verify that the other device can handle the codec
		conversation or that a transcoder is in place to handle the service.
		See the “Call Statistics Screen” section on page 6-10for information about displaying
		these statistics.

	Cisco Unified IP Phone 7960G/7940G Administration Guide for Cisco Unified Communications Manager 7.0 (SCCP)
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