Specifications
Table Of Contents
- Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified CallManager Release 4.1, 4.2, 5.0 and Later
- Contents
- Preface
- An Overview of the Cisco Unified Wireless IP Phone 7921G
- An Overview of the Voice Over IP Wireless Network
- Understanding the Wireless LAN
- Components of the VoIP Wireless Network
- Voice Over IP Wireless Network Configuration
- Site Survey Verification
- Setting Up the Cisco Unified Wireless IP Phone 7921G
- Before You Begin
- Installing the Cisco Unified Wireless IP Phone 7921G
- Powering On the Cisco Unified Wireless IP Phone 7921G
- Understanding the Phone Startup Process
- Using the Cisco Unified Wireless IP Phone 7921G Web Pages
- Using the USB Connection for Initial Phone Configuration
- Updating Phones Remotely
- Configuring Network Profiles
- Configuring USB Settings
- Configuring Trace Settings
- Using System Settings
- Configuring Settings on the Cisco Unified Wireless IP Phone 7921G
- Accessing Network and Phone Settings
- Configuring Network Profile Settings
- Changing Phone Settings
- Configuring the Security Certificate on the Phone
- Changing the USB Configuration
- Configuring Features, Templates, Services, and Users
- Configuring Cisco Unified Wireless IP Phones in Cisco Unified CallManager
- Telephony Features Available for the Phone
- Specific Configuration Options for the Cisco Unified Wireless IP Phone 7921G
- Configuring Softkey Templates
- Modifying Phone Button Templates
- Setting Up Services
- Configuring Corporate and Personal Directories
- Adding Users to Cisco Unified CallManager
- Managing the User Options Web Pages
- Creating Custom Phone Rings
- Viewing Security, Device, Model, and Status Information on the Phone
- Monitoring the Cisco Unified Wireless IP Phone Remotely
- Troubleshooting the Cisco Unified Wireless IP Phone 7921G
- Resolving Startup and Connectivity Problems
- Resolving Voice Quality and Roaming Problems
- General Troubleshooting Information
- Erasing the Local Configuration
- Providing Information to Users By Using a Website
- Supporting International Users
- Physical and Operating Environment Specifications
- Checklist for Deploying the Cisco Unified Wireless IP Phone 7921G
- Index
Chapter 2 An Overview of the Voice Over IP Wireless Network
Components of the VoIP Wireless Network
2-14
Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified CallManager Release 4.1, 4.2, 5.0
OL-10802-02
• Traffic Specification (TSpec)—The TSpec value is used to calculate call
limits and WLAN load balancing. The TSpec value of each voice stream
allows the system to allocate bandwidth to voice devices on a first-come,
first-served basis. For more information, see
“Voice Quality in a Wireless
Network” section on page 2-16.
The unified IP phone associates with the access point with the highest RSSI and
lowest channel utilization values (QBSS) that have matching SSID and encryption
types.To insure that voice traffic will be handled properly, you must configure the
correct QoS in the access point. For configuration information, see
“Wireless
Network Requirements for VoIP” section on page 2-27.
Related Topics
• Roaming in a Wireless Network, page 2-14
• Security for Voice Communications, page 2-6
• Voice Over IP Wireless Network Configuration, page 2-27
Roaming in a Wireless Network
Wireless IP phones provide communication mobility to users within the enterprise
WLAN environment. Unlike cellular phones that have broad coverage, the
coverage area for the unified IP
phone is smaller; therefore, phone users
frequently roam from one access point to another. To understand some of the
limitations of roaming with wireless IP phones, these examples provide
information about the WLAN environment.
• Pre-call Roaming—A wireless IP phone user powers on the phone in the
office, and the phone associates with the nearby access point. The user leaves
the building, moves to another building, and then places a call. The phone
associates with a different access point in order to place the call from the new
location. If the associated access point is within the same Layer 2 VLAN, the
IP address remains the same for the phone. But, if the roaming phone crosses
a Layer 3 boundary with DHCP enabled, the phone recognizes that it is no
longer in the same subnet. The phone requests a new IP address before it can
connect to the network and place the call.