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 4-3 for

 

details.

 

 

Phone resetting.

The phone resets when it loses contact with the

 

Cisco Unified CallManager 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

delay.

the keys too quickly, some of them might not be recognized.

 

 

Loopback condition.

A loopback condition can occur when the following conditions

 

are met:

 

• The SW Port Configuration option in the Network

 

Configuration menu on the phone is set to 10 Half

 

(10-BaseT / half duplex)

 

• The phone receives power from an external power supply.

 

• The phone is powered down (the power supply is

 

disconnected).

 

In this case, the switch port on the phone can become disabled

 

and the following message will appear in the switch console

 

log:

 

HALF_DUX_COLLISION_EXCEED_THRESHOLD

 

To resolve this problem, re-enable the port from the switch.

 

 

 

Cisco Unified IP Phone 7906G and 7911G Administration Guide for Cisco Unified CallManager

9-14

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Cisco Systems 7906G, 7911G manual Unlocking and Locking Options section on page 4-3 for, Halfduxcollisionexceedthreshold
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7906G, 7911G specifications

The Cisco Systems 7911G is a versatile IP phone designed to enhance communication in enterprise environments. Targeting workers in various organizational settings, this model is known for its reliability, ease of use, and robust features that cater to both basic and advanced telephony requirements.

One of the key features of the Cisco 7911G is its support for Voice over IP (VoIP) technology. Using this technology allows for the transmission of voice signals over the internet rather than through traditional telephone lines. This not only reduces telephony costs but also offers enhanced functionality that integrates seamlessly with existing communication systems.

The phone is equipped with a monochrome graphical display that provides users with clear visibility of their call status, directory information, and menu options. With a resolution of 128x64 pixels, the screen is large enough to offer important information without overwhelming the user. This simplicity makes it an ideal choice for users who require straightforward functionality without the complexity of advanced features.

Ergonomically designed, the Cisco 7911G features a comfortable keypad with dedicated buttons for frequently used functions such as mute, hold, and transfer. It supports multiple lines, providing users with the ability to manage multiple calls simultaneously. Additionally, it offers programmable line keys that can be customized for speed dial or as soft keys for quick access to features.

The device supports Power over Ethernet (PoE), which allows the phone to receive power through the network cable rather than needing a separate power source. This feature not only simplifies installation but also enhances mobility within the workspace, as it reduces cable clutter.

Another significant characteristic of the Cisco 7911G is its compatibility with Cisco Unified Communications Manager, which ensures centralized management of telephony systems. It also supports a range of audio codecs that help in delivering high-quality audio during calls, reducing latency and improving overall communication quality.

Security is also a focus with the Cisco 7911G, as it features a secure access feature that includes Transport Layer Security (TLS) and Secure Real-Time Transport Protocol (SRTP) for encrypted voice communications. This ensures that sensitive conversations are protected from eavesdropping.

Overall, the Cisco Systems 7911G is a reliable, feature-rich IP phone that provides an excellent solution for organizations looking to upgrade their communication systems. Its combination of user-friendly design, powerful integrations, and security features makes it a cornerstone in the suite of Cisco telecommunications solutions.
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