Specifications

9-7
Cisco Unified IP Phone 7906G and 7911G for Cisco Unified Communications Manager 8.0
OL-21033-01
Chapter 9 Troubleshooting and Maintenance
Cisco Unified IP Phone Resets Unexpectedly
Verifying DHCP Settings
The following suggestions can help you determine if the phone has been properly configured to use
DHCP:
1. Verify that you have properly configured the phone to use DHCP. See Network Configuration Menu,
page 4-5 for more information.
2. Verify that the DHCP server has been set up properly.
3. Verify the DHCP lease duration. Cisco recommends that you set it to 8 days.
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.
Checking Static IP Address Settings
If the phone has been assigned a static IP address, verify that you have entered the correct settings. See
Network Configuration Menu, page 4-5 for more information.
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 switch as phone), it is likely that you do not have
a voice VLAN configured. Isolating the phones on a separate auxiliary VLAN increases the quality of
the voice traffic.
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.
You can check whether a Cisco Unified IP Phone received a command from
Cisco Unified Communications Manager to reset by pressing the Applications Menu button on the
phone and choosing Settings > Status > Network Statistics. If the phone was recently reset one of these
messages appears: