2-5
Cisco Unified IP Phone 6921, 6941, 6945, and 6961 Administration Guide for Cisco Unified Communications Manager 8.5 (SCCP and SIP)
OL-23769-01
Chapter
Understanding Phone Configuration Files

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, 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.
Note If the device security mode in the configuration file is set to secure, but the phone has not received a
CTL file, the phone tries four times to obtain a CTL file so it can register securely.
Note Cisco Extension Mobility Cross Cluster is an exception, in that the phone permits a TLS connection to
Cisco Unified CM for secure signaling even without the CTL file.
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