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Cisco ATA 187 Analog Telephone Adaptor Administration Guide for SIP (Version 1.0)

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Chapter 2 Preparing to Install the ATA 187 on Your Network

Understanding Phone Configuration Files

Configuration files for a phone are stored on the TFTP server and define parameters for connecting to
Cisco Unified Communications Manager. In general, any time you make a change in Cisco
Unified Communications Manager that requires the phone to be reset, a change is automatically made
to the phone’s configuration file. If the system needs to reset or restart, both ports must reset or restart
at the same time.

Configuration files also contain information about which image load the phone should be running. If this
image load differs from the one that is currently loaded on a phone, the phone contacts the TFTP server
to request the required load files. (These files are digitally signed to ensure the authenticity of the file
source.)

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 Communications Manager, the phone establishes
a TLS connection to Cisco Unified Communications Manager. Otherwise, the phone establishes a TCP
connection. For SIP phones, a TLS connection requires that the transport protocol in the phone
configuration file be set to TLS, which corresponds to the transport type in the SIP Security Profile in
Cisco Unified Communications Manager.

Note

If the device security mode in the configuration file is set to Authenticated or Encrypted, but the phone
has not received a CTL file, the phone tries four times to obtain it 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 Communications Manager for secure signaling even without the CTL file.

If you configure security-related settings in Cisco Unified Communications Manager Administration,
the phone configuration file will contain sensitive information. To ensure the privacy of a configuration
file, you must configure it for encryption. For detailed information, see

Configuring Encrypted Phone

Configuration Files

Cisco Unified Communications Manager Security Guide

A phone accesses a default configuration file named XmlDefault.cnf.xml only when the phone has not
received a valid Trust List file containing a certificate assigned to the Cisco Unified Communications
Manager and TFTP.

If auto registration is not enabled and you did not add the phone to the Cisco Unified Communications
Manager database, the phone does not attempt to register with Cisco Unified Communications Manager.
The phone continually displays the “Configuring IP” message until you either enable auto-registration
or add the phone to the Cisco Unified Communications Manager database.

If the phone has registered before, the phone accesses the configuration file named
ATA<

mac_address>

.cnf.xml, where

mac_address

is the MAC address of the phone.

For SIP phones, the TFTP server generates these SIP configuration files:

•

SIP IP Phone:

–

For unsigned and unencrypted files—ATA

<mac>

.cnf.xml