I search and searched for how to do this but most of the steps were using the most awesome and free asterisk server but none on how to do it on your corporate network (Which I don’t advise but well what the hell, I am not responsible if you get in trouble). I came across this blog like 10 pages in on google and well from 2005, but it still applied.

Here are the steps:

1. You’ll need a tftp server either on windows on *nix, you can find many on google like this one.
2. Go to Settings -> Network Configuration
3. Hit * * #. Nothing will happen, but you’ve just made the settings editable.
4. Find the Alternate TFTP setting. On my phone it’s #32. Set it to “Yes” by hitting the appropriate soft button.
5. Go back up to the “TFTP Server 1? setting (#8 on my phone), and hit the “Edit” soft button
Write down the current TFTP server. We’ll need it later, and you should probably store it in a safe place, just in case something dies sometime down the road.
6. Type in your new TFTP server IP.
7. Save the changes.

The phone will reboot, this is key, you need to watch your tftp server for what files the phone is requesting. For me it was a few xml files you’ll need to get these files from your original tftp server. Once you have all the files reboot the phone again, t the phone will ask for files that aren’t on either server that’s fine. Edit your ringlist.xml and add your ring tones, the cisco format is very specific so I used sox and this command sox -t wav ring.wav -t raw -r 8000 -U -b -c 1 ring.raw resample -ql this seemed to produce the best results.

Now you’re all set with custom rings on your office phone, if needed you can always use the same steps to go back to your official tftp server.