Determine Dns Or Connectivity Issues; General Troubleshooting Information; Step 1 - Cisco 3905 Administration Manual

Troubleshooting and Maintenance

Determine DNS or Connectivity Issues

If the phone continues to reset, follow these steps to eliminate DNS or other connectivity errors:
Procedure

Step 1

Use the Reset Settings menu to reset phone settings to their default values. See the
Reset or Restore, on page 92
Step 2
Modify DHCP and IP settings:
a) Disable DHCP. See the
b) Assign static IP values to the phone. See the
same default router setting used for other functioning Cisco Unified IP Phones.
c) Assign a TFTP server. See the
server used for other functioning Cisco Unified IP Phones.
Step 3
On the Cisco Unified Communications Manager server, verify that the local host files have the correct
Cisco Unified Communications Manager server name mapped to the correct IP address.
Step 4 From Cisco Unified Communications Manager, choose System > Server and verify that the server is referred
to by its IP address and not by its DNS name.
Step 5 From Cisco Unified Communications Manager, choose Device > Phone > Find and verify that you have
assigned the correct MAC address to this Cisco Unified IP Phone. For information about determining a MAC
address, see the
Step 6 Power cycle the phone.

General Troubleshooting Information

The following table provides general troubleshooting information for the Cisco Unified IP Phone.
Table 19: Cisco Unified IP Phone Troubleshooting
Summary
Connecting a Cisco Unified IP Phone to another
Cisco Unified IP Phone.
Prolonged broadcast storms cause IP phones to
reset, or be unable to make or answer a call.
for details.
Configuration Menus, on page 35
Configuration Menus, on page 35
MAC Address for Cisco Unified IP Phone Determination, on page
Cisco Unified SIP Phone 3905 Administration Guide for Cisco Unified Communications Manager 8.6 (SIP)
General Troubleshooting Information
for instructions.
Configuration Menus, on page 35
for instructions. Use the same TFTP
Explanation
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.
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.
Cisco Unified IP Phone
for instructions. Use the
29.
89