Cisco 7912G - Manual (Page 112)

Chapter 7 Troubleshooting the Cisco Unified IP Phone
Cisco Unified IP Phone Resets Unexpectedly
7-8
Cisco Unified IP Phone Administration Guide for Cisco Unified CallManager 5.0 (SIP), Cisco Unified IP Phones
OL-8131-01
Cisco Unified IP Phone Resets Unexpectedly
If users report that their phones are resetting during calls or resetting while idle
on their desk, you should investigate the cause. If the network connection and
Cisco Unified CallManager 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 CallManager. These sections can help you identify the cause of
a phone resetting in your network:
• Verifying Physical Connection, page 7-8
• Identifying Intermittent Network Outages, page 7-8
• Verifying DHCP Settings, page 7-9
• Checking Static IP Address Settings, page 7-9
• Verifying Voice VLAN Configuration, page 7-9
• Verifying that the Phones Have Not Been Intentionally Reset, page 7-9
• Eliminating DNS or Other Connectivity Errors, page 7-10
Verifying Physical Connection
Verify that the Ethernet connection to which the Cisco Unified IP Phone is
connected is up. For example, check if the particular port or switch to which the
phone is connected is down.
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.