Cisco 7971G-GE Administration Guide - Page 172

General Troubleshooting Tips Chapter 9 Troubleshooting and Maintenance Table 9-1 Cisco Unified IP Phone Security Troubleshooting (continued) Problem Possible Cause Factory Reset Deleted 802.1X Shared Secret Phone cannot obtain a DHCP-assigned IP address These errors typically indicate that the phone has Phone does not register with Cisco Unified Communications Manager Phone status display as "Configuring IP" or "Registering" completed a factory reset (see the "Performing a Factory Reset" section on page 9-14) while 802.1X was enabled. A factory reset deletes the shared secret, which is required for 802.1X authentication and network access. To resolve this, Cannot access phone menus to verify 802.1X you have two options: status • Temporarily disable 802.1X authentication on the switch. • Temporarily move the phone to a network environment that is not using 802.1X authentication. Once the phone starts up normally in one of these conditions, you can access the 802.1X configuration menus and re-enter the shared secret (see the "802.1X Authentication and Status" section on page 4-31). General Troubleshooting Tips Table 9-2 provides general troubleshooting information for the Cisco Unified IP Phone. Table 9-2 Cisco Unified IP Phone Troubleshooting Summary Explanation Daisy-chaining IP phones Cisco does not support connecting an IP phone to another IP phone through the PC port. Each IP phone should directly connect to a switch port. If phones are connected together in a line (by using the PC port), the phones will not work. Poor quality when calling mobile In Cisco Unified Communications Manager, you can configure the phones using the G.729 protocol network to use the G.729 protocol (the default is G.711). When using G.729, calls between an IP phone and a mobile phone will have poor voice quality. Use G.729 only when absolutely necessary. Prolonged broadcast storms cause IP phones to reset, or be unable to make or answer a call A prolonged Layer 2 broadcast storm (lasting several minutes) on the voice VLAN may cause IP phones to reset, lose an active call, or be unable to initiate or answer a call. Phones may not come up until a broadcast storm ends. 9-10 Cisco Unified IP Phone 7970G/7971G-GE Administration Guide for Cisco Unified Communications Manager 7.0 OL-15299-01