Cisco Systems 7970G manual Unlocking and Locking Options section on page 4-4 for

Chapter 9 Troubleshooting and Maintenance

General Troubleshooting Tips

Table 9-2	Cisco Unified IP Phone Troubleshooting (continued)
Summary		Explanation
Changing the telephone		By default, the network configuration options are locked to
configuration		prevent users from making 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 4-4 for
		details.
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		When you are on a call that requires keypad input, if you press
(DTMF) delay		the keys too quickly, some of them might not be recognized.
Codec mismatch between the phone		The RxType and the TxType statistics show the codec that is
and another device		being used for a conversation between this Cisco
		Unified IP phone and the other device. These 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 7-16 for
		information about displaying these statistics.
Sound sample mismatch between the		The RxSize and the TxSize statistics show the size of the voice
phone and another device		packets that is being used a conversation between this Cisco
		Unified IP phone and the other device. The values of these
		statistics should match.
		See the “Call Statistics Screen” section on page 7-16 for
		information about displaying these statistics.
Gaps in voice calls		Check the AvgJtr and the MaxJtr statistics. A large variance
		between these statistics might indicate a problem with jitter on
		the network or periodic high rates of network activity.
		See the “Call Statistics Screen” section on page 7-16 for
		information about displaying these statistics.

	Cisco Unified IP Phone Administration Guide for Cisco Unified CallManager 5.1 (SIP), Cisco Unified IP Phones
9-16	OL-11524-01