IP Phone, SIP Phone Registration Process with CUCM

Posted: June 1, 2012 in CUCM

SIP Phone Registration Process

SIP Phones use a different set of steps to achieve the same goal. Steps 1 to 4 are the same as SCCP Phones, refer the steps as illustrated in the figure: SCCP Phone Boot Process .

1- The phone contacts the TFTP server and requests the Certificate Trust List file (only if the cluster is secured).
2- The phone contacts the TFTP server and requests its SEP<mac-address>.cnf.xml configuration file.
3- If the SIP Phone has not been provisioned before boot time, the SIP Phone downloads the default configuration XMLDefault.cnf.xml file from the TFTP server.
4- The SIP phone requests a firmware upgrade (Load ID file), if one was specified in the configuration file. This process allows the phone to upgrade the firmware image automatically when required for a new version of CUCM.
5- The phone downloads the SIP dial rules configured for that phone.
6- The phone Establish connection with the primary CUCM and the TFTP server end to end.
7- The phone Registers with the primary CUCM server listed in its configuration file.
8- The phone downloads the appropriate localization files from TFTP.
9- The phone downloads the softkey configurations from TFTP.
10- The phone downloads custom ringtones (if any) from TFTP.

About TFTP server:

TFTP is a critical service for IP Phones. The Phone use TFTP to download their config files, firmware and other data. Without TFTP, the phones simply do not function properly. When you make a configuration change to a device, CUCM creates or modifies a config file for the device and uploads it to the TFTP server. TFTP service much therefore provided by one or more CUCM servers in the cluster.

Note: A generic TFTP server will not have the integrated capability that a CUCM TFTP server does and will not correctly fulfill the role.

  1. Priyavart Rathi says:

    Hi Team,

    This type of Blog’s are very help for New comers. and i relay appreciate for this.

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