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.

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

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:

CP7912080000SIP060111A.ZIP

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

Next:

run:


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


Done!

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.

Greetings!

P.D. For debugging Process you can install Wireshark