Cisco Systems 8961 manual General Troubleshooting Tips, Summary Explanation, 12-10

Chapter 12 Troubleshooting and Maintenance

General Troubleshooting Tips

Table 12-1 Cisco Unified IP Phone Security Troubleshooting (continued)

Problem

Possible Cause

802.1X Not Enabled

Phone cannot obtain a DHCP-assigned IP address

Phone does not register with Cisco Unified Communications Manager

Phone status display as “Configuring IP” or “Registering”

802.1X Authentication Status displays as “Disabled”

Status menu displays DHCP status as timing out

These errors typically indicate that 802.1X authentication is not enabled on the phone. To enable it, see the “802.1X Authentication and Transaction Status” section on page 7-15.

Factory Reset Deleted 802.1X Shared Secret

Phone cannot obtain a DHCP-assigned IP address

Phone does not register with Cisco Unified Communications Manager

Phone status display as “Configuring IP” or “Registering”

Cannot access phone menus to verify 802.1X status

These errors typically indicate that the phone has completed a factory reset (see the “Resetting the Cisco Unified IP Phone” section on page 12-15) 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, temporarily move the phone to a network environment that is not using 802.1X authentication.

Once the phone starts up normally, you can access the 802.1X configuration menus to enable device authentication and to re-enter the shared secret (see the “802.1X Authentication and Transaction Status” section on page 7-15).

General Troubleshooting Tips

Table 12-2provides general troubleshooting information for the Cisco Unified IP Phone.

Table 12-2 Cisco Unified IP Phone Troubleshooting

Summary	Explanation
Connecting a Cisco Unified IP Phone to	Cisco does not support connecting an IP phone to another IP phone through the
another Cisco Unified IP Phone	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 with tandem audio encoding	Tandem encoding can occur when making calls between an IP phone and a
	digital cellular phone, when using a conference bridge, or in situations where IP
	to IP calls are partially routed across the PSTN. In these cases, use of voice
	codecs such as G.729 and iLBC may result in poor voice quality. Use these
	codecs only when absolutely necessary.
Prolonged broadcast storms cause IP	A prolonged Layer 2 broadcast storm (lasting several minutes) on the voice
phones to reset, or be unable to make or	VLAN may cause IP phones to reset, lose an active call, or be unable to initiate
answer a call	or answer a call. Phones may not come up until a broadcast storm ends.

	Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.5 (SIP)
12-10	OL-20861-01