Information Technology Reference
In-Depth Information
If the phone cannot obtain a specific configuration file because, for example, CUCM is using autoregistration, the phone
requests a default configuration file (XMLDefault.cnf.xml). Information included in the configuration file requested from the
TFTP server includes a list of up to three CUCMs in a CUCM group, phone load information, network and user locales, and
URLs.
If the load information contained in the configuration file indicates that the phone is running an old image, it downloads the
latest image from the TFTP server and reboots.
6.
Finally, the phone registers with a Cisco CUCM.
After the phone obtains a configuration file from the TFTP server, it opens a connection to the CUCM server (the highest-
priority server available in the CUCM group list contained in the configuration file). Assuming that the phone has been
manually configured or autoregistration has been enabled, the CUCM server then supplies a DN and other information,
including softkey template and phone button template information, and the phone becomes usable.
NTP
It is essential to synchronize time between CallManager/CUCM and other servers and devices to be able to troubleshoot problems in
an IP telephony network. For example, if a problem occurs and you need to be able to examine events that occur across trace files on
multiple servers, it might be impossible to accurately diagnose what is happening if those servers' clocks are not synchronized.
The clocks for servers and other devices can be synchronized across a network using the Network Time Protocol (NTP).
It is possible to configure automatic synchronization on CallManager 4.x servers by ensuring that the Windows 2000
NetworkTimeProtocol service has its Startup Type set to automatic (via the Control Panel), configuring the ntp.conf file (found in
C:\WINNT\) to point to the desired NTP servers or specifying the reception of NTP broadcasts, and finally stopping and starting the
NetworkTimeProtocol service.
It is also possible to manually synchronize time on CUCM servers by stopping the NetworkTimeProtocol service, using the ntpdate
server_ip_address or ntpdate router_ethernet_i/f_address command, and then restarting the NetworkTimeProtocol service.
You can add a phone NTP reference in CUCM by navigating to System, Phone NTP Reference . You can then assign the NTP
reference to a Date/Time group, and the Date/Time group is then assigned to a device pool.
 
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