How to change Cisco 7912 Standard Firmware to SIP

bitfrost's picture

Hi, after hours working, I finally get how to change Cisco 7912 IP Phone to Work with SIP Protocol, here are the steps:

First, we need a TFTP server

I am going to use Ubuntu 10.04, but you can do it with other distributions as well.

sudo apt-get install atftp

With your preferred editor, edit the file /etc/default/atftpd

OPTIONS="--tftpd-timeout 300 --retry-timeout 5 --mcast-port 1758 --mcast-ttl 1 --maxthread 100 --verbose=5 /tftpboot"

After that restart the system because, it will lock to he inetd, or just kill the process that is locked with inetd.

Make the directory /tftpboot, and give it permission to 777 and owner to: nobody

Restart the service

invoke-rc.d atftpd start

Now we have a working tftp server.

We need the firmware files, by copyright policies I can't post it here, the name of the file is:


Now give execution permissions to the file:

chmod 700 cfgfmt.linux

Change in gkDefault.txt this part:

upgradecode:3,0x601,0x0400,0x0100,your server IP,69,0x060111a,CP7912080000SIP060111A.sbin



./cfgfmt.linux -tsip_ptag.dat gkdefault.txt gkdefault.cfg


Now, change the alternate tftp server to Point your Server Address, and restart the Phone, (you can unlock the phone with **#)

If everything goes well you now will have the Cisco 7912 SIP Ready.


P.D. For debugging Process you can install Wireshark

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bitfrost's picture

Fichero .xml para Ciertos 7912 "RUDITOS"