Chapter 2 Preparing to Install the Cisco Unified IP Phone on Your Network
Understanding the Phone Startup Process
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Cisco Unified IP Phone Administration Guide for Cisco Unified CallManager 4.2, Cisco Unified IP Phones
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Understanding Phone Configuration Files
Configuration files for a phone are stored on the TFTP server and define
parameters for connecting to Cisco Unified CallManager. In general, any time
you make a change in Cisco Unified CallManager that requires the phone to be
reset, a change is made to the phone’s configuration file automatically.
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 new image file.
In addition, if the device security mode in the configuration file is set to
Authenticated, the phone contains a valid LSC, and the CTL file on the phone has
a valid certificate for Cisco Unified CallManager, the phone establishes a TLS
connection to Cisco Unified CallManager. Otherwise, the phone establishes a
TCP connection.
Note If the device security mode in the configuration file is set to Authenticated or
Encrypted but the phone does not contain a valid LSC or the CTL file on the phone
does not have a valid certificate for Cisco Unified CallManager, the phone will
continuously try to obtain a CTL file or try to install a valid certificate so that it
can register securely.
A phone requests a configuration file whenever it resets and registers with
Cisco Unified CallManager.
Note If a phone receives a CTL file with a valid certificate for the TFTP server, the
phone requests a signed.cnf.xml.sgn configuration file instead the .cnf.xml file.
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 CallManager
• The phone has not been added to the Cisco Unified CallManager Database
• The phone is registering for the first time
• The phone encounters an error while attempting to retrieve its configuration
file from the TFTP server
All other times, a phone accesses a .cnf.xml file corresponding to its device name.
