Cisco 6921 Administration Guide

2-5
Cisco Unified IP Phone 6921, 6941, 6945, and 6961 Administration Guide for Cisco Unified Communications Manager 8.6 (SCCP and SIP)
OL-24567-01
Chapter
Understanding Phone Configuration Files
Power Outage
Your accessibility to emergency service through the phone is dependent on the phone being powered. If
there is an interruption in the power supply, Service and Emergency Calling Service dialing will not
function until power is restored. In the case of a power failure or disruption, you may need to reset or
reconfigure equipment before using the Service or Emergency Calling Service dialing.
Obtaining Additional Information about Power
For related information about power, refer to the documents shown in Table 2-2. These documents
provide information about the following topics:
• Cisco switches that work with the Cisco Unified IP Phone 6921, 6941, 6945, and 6961
• The Cisco IOS releases that support bidirectional power negotiation
• Other requirements and restrictions regarding power
Understanding Phone Configuration Files
Configuration files for a phone are stored on the TFTP server and define parameters for connecting to
Cisco Unified CM. In general, any time you make a change in Cisco Unified CM that requires the phone
to be reset, a change is automatically made to the phone’s configuration file.
Configuration files also contain information about which image load the phone should be running. If this
image load differs from the one currently loaded on a phone, the phone contacts the TFTP server to
request the required load files.
A phone accesses a default configuration file named XmlDefault.cnf.xml from the TFTP server when
the following conditions exist:
• You have enabled auto-registration in Cisco Unified CM
• The phone has not been added to the Cisco Unified CM database
• The phone is registering for the first time
In addition, if the device security mode in the configuration file is set to Authenticated and the CTL file
on the phone has a valid certificate for Cisco Unified CM, the phone establishes a TLS connection to
Cisco Unified CM. Otherwise, the phone establishes a TCP connection.
Table 2-2 Related Documentation for Power
Document Topics URL
Cisco Unified IP Phone Power
Injector
http://www.cisco.com/en/US/products/ps6951/index.html
PoE Solutions http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/inde
x.html
Cisco Catalyst Switches http://cisco.com/en/US/products/hw/switches/index.html
Integrated Service Routers http://www.cisco.com/en/US/products/hw/routers/index.html
Cisco IOS Software http://www.cisco.com/en/US/products/sw/iosswrel/products_ios_
cisco_ios_software_category_home.html

Cisco 6921 Specifications

General

Brand	Cisco
Model	6921
Category	IP Phone
Language	English