Filter
Top Products
12-6
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager 8.5 (SIP)
OL-20861-01
Chapter 12 Troubleshooting and Maintenance
Cisco Unified IP Phone Resets Unexpectedly
Symptom: Cisco Unified IP Phone Unable to Obtain IP Address
If a phone is unable to obtain an IP address when it starts up, the phone may be not be on the same
network or VLAN as the DHCP server, or the switch port to which the phone is connected may be
disabled. Make sure that the network or VLAN to which the phone is connected has access to the DHCP
server, and make sure that the switch port is enabled.
Cisco Unified IP Phone Resets Unexpectedly
If users report that their phones are resetting during calls or while idle on their desk, you should
investigate the cause. If the network connection and Cisco Unified Communications Manager
connection are stable, a Cisco Unified IP Phone should not reset on its own.
Typically, a phone resets if it has problems connecting to the Ethernet network or to Cisco Unified
Communications Manager. These sections can help you identify the cause of a phone resetting in your
network:
• Verifying the Physical Connection, page 12-6
• Identifying Intermittent Network Outages, page 12-6
• Verifying DHCP Settings, page 12-7
• Checking Static IP Address Settings, page 12-7
• Verifying the Voice VLAN Configuration, page 12-7
• Verifying that the Phones Have Not Been Intentionally Reset, page 12-7
• Eliminating DNS or Other Connectivity Errors, page 12-8
Verifying the Physical Connection
Verify that the Ethernet connection to which the Cisco Unified IP Phone is connected is up. For example,
check whether the particular port or switch to which the phone is connected is down and that the switch
is not rebooting. Also make sure that there are no cable breaks.
Identifying Intermittent Network Outages
Intermittent network outages affect data and voice traffic differently. Your network might have been
experiencing intermittent outages without detection. If so, data traffic can resend lost packets and verify
that packets are received and transmitted. However, voice traffic cannot recapture lost packets. Rather
than retransmitting a lost network connection, the phone resets and attempts to reconnect its network
connection.
If you are experiencing problems with the voice network, you should investigate whether an existing
problem is simply being exposed.