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 9 Troubleshooting the Cisco Unified Wireless IP Phone 7921G
Resolving Voice Quality and Roaming Problems
9-12
Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified CallManager Release 4.1, 4.2, 5.0
OL-10802-02
Identifying Intermittent Network Outages
Intermittent network outages affect data and voice traffic differently. Your
network might have been experiencing intermittent outages without detection. If
so, data traffic can resend lost packets and verify that packets are received and
transmitted. However, voice traffic cannot recapture lost packets. The phone can
retransmit and attempt to recover, or if the phone reaches the maximum retransmit
rate, it drops the packets or loses association with the access point.
If you are experiencing problems with the voice network, you should investigate
whether an existing problem is simply being exposed.
Verifying DHCP Settings
To determine if the phone has been properly configured to use DHCP, follow these
steps:
Step 1 Verify that you have properly configured the phone to use DHCP. See the
“Configuring DHCP Settings” section on page 5-8 for details.
Step 2 Verify that the DHCP server has been set up properly.
Step 3 Verify the DHCP lease duration. Your local policy determines this setting.
Cisco Unified IP Phones send messages with request type 151 to renew their
DHCP address leases. If the DHCP server expects messages with request type
150, the lease will be denied, forcing the phone to restart and request a new IP
address from the DHCP server.
Verifying Voice VLAN Configuration
If the Cisco Unified IP Phone appears to reset during heavy network usage (for
example, following extensive web surfing on a computer connected to same
access point and switch as phone), it is likely that you do not have a voice VLAN
or the appropriate QoS settings configured.
By isolating the wireless phones on a separate auxiliary VLAN, you can use QoS
to prioritize the voice traffic over data traffic and improve the voice quality. See
the
“Voice Quality in a Wireless Network” section on page 2-16 for details.