IP Phone, SCCP Phone Registration Process with CUCM

Posted: June 1, 2012 in CUCM

IP Phone Registration Process with the Cisco Unified Communications Manager (CUCM). It covers both SCCP and SIP Phone Registration Process to help the beginners to understand the basics of IP Phone boot process better which will help in Configuration and Troubleshooting the Network related issues easily.

SCCP IP Phone Registration Process

1- SCCP phone obtains the Power (PoE or AC adapter).
2- The phone loads its locally stored firmware image.
3- The phone learns the Voice VLAN ID via CDP from the switch.
4- The phone uses DHCP to learn its IP address, subnet mask, default gateway and TFTP server address.
5- The phone contacts the TFTP server and requests its configuration file. Each phone has a customized configuration file

named SEP<mac_address>.cnf.xml created by CUCM and uploaded to TFTP when the administrator creates or modifies the phone.

6. The phone registers with the primary CUCM server listed in its configuration file. CUCM then sends the softkey template to the phone using SCCP messages.

What is in that SEP<mac_address>.cnf.xml file ?

This file contains a list of CUCM server, in order, that the phone should register with. It lists teh TCP ports it should use for SCCP communication. It also lists the firmware version for each device model and the service URLs that each device should be using.

The CUCM server sends other configurations such as DNs, softkeys and speed dials via the SCCP messages in the last phase of the registration process.

  1. Mihail Petreski says:

    Hi mate,
    Do you have any documentation or advice for configuring a remote Load Server to act as a TFTP?
    I’d like to use Peer Firmware Sharing and a Load Server, is this possible?


    • Network Experts Blog says:

      thnaks Mihail, sorry for late reply i was away from my blog, however I don’t understand your question, however remote load server means you are uploading firmware on remote load server and one boot process initiate then it load from remote server … is that goal are you trying to achieve ??? or pls explain in detail your question ?

      • mihail says:

        I worked it out in the end, quite simple really I just built a tftp server with the phone firmware and assigned it to each phone in the load server field.

        My tftp server is a windows box with all the firmware files

        My main question was if the tftp server is unavailable when the phone boots is that a problem?
        At a guess if the phone is already on the default load then it shouldnt need to talk to the tftp server as it already has the firmware installed and should just boot as normal. Is that right?

      • Network Experts Blog says:

        Yes TFTP server required when phone boots up, it will look for cnf.xml file doesn’t matter it has firmware loaded … it will always look for configuration file from call manager/TFTP server …HTH 🙂

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