Cisco 7921G Administration Guide - Page 195

Chapter 10 Troubleshooting the Cisco Unified Wireless IP Phone 7921G Resolving Voice Quality and Roaming Problems 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 QoS in a Wireless Network" section on page 2-10 for details. Verifying that the Phones Have Not Been Intentionally Reset If you are not the only administrator with access to Cisco Unified Communications Manager, you should verify that no one else has intentionally reset the phones. Eliminating DNS or Other Connectivity Errors If the phone does not register with Cisco Unified Communications Manager, check to see if you are using host names or IP addresses for Cisco Unified Communications Manager servers. To eliminate DNS or other connectivity errors, follow these steps: Procedure Step 1 Step 2 Step 3 Reset the phone to factory defaults. See the "Erasing the Local Configuration" section on page 10-18 for details. Modify DHCP and IP settings: a. Disable DHCP. See the "Configuring DHCP Settings" section on page 5-6 for details. b. Assign static IP values to the phone. See the "Configuring DHCP Settings" section on page 5-6 for details. Use the same default router setting used for other functioning Cisco Unified IP Phones. c. Assign a TFTP server. See the "Configuring an Alternate TFTP Server" section on page 5-7 for details. Use the same TFTP server used for other functioning Cisco Unified IP Phones. From Cisco Unified Communications Manager, choose System > Server and verify that the server is referred to by its IP address and not by its host name. Note Cisco recommends that you configure IP addresses only and not host names to eliminate the DNS resolution in the phone registration process. OL-15985-01 Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified Communications Manager Release 7.0 10-9