You can find specifics regarding the required CUCM ringtone file type in your phones administration guide. One example is here: http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7965g_7945g/6_1/english/administration/guide/7965cst.html#wp1h088184
Download a ringtone to a SFTP server. I am using FreeFTPd from http://www.freesshd.com/ on a Win7 laptop.
Just a note about FreeFTPd... I would suggest NOT installing it as a service if you only run it occasionally as administration is much easier, and if on Win7, when starting the application, right click and run as administrator to allow changes being committed to the FreeFTPd config (i.e. users, home directories, etc.).
Here's an example of how to download a ringtone (in this case, Vibe) via the CUCM CLI:
login as: platformadministrator
Command Line Interface is starting up, please wait ...
Welcome to the Platform Command Line Interface
2 vCPU: Intel(R) Xeon(R) CPU E5506 @ 2.13GHz
Disk 1: 80GB
4096 Mbytes RAM
admin:file get tftp Vibe.raw
Please wait while the system is gathering files info ...done.
Sub-directories were not traversed.
Number of files affected: 1
Total size in Bytes: 16080
Total size in Kbytes: 15.703125
Would you like to proceed [y/n]? y
SFTP server IP: 192.168.111.112
SFTP server port :
User ID: sftp
Download directory: /
Since the ring files are in a headerless / RAW format, you'll need an application to open, play and manipulate them, accordingly. I use Audacity from http://audacity.sourceforge.net/.
Audacity will not know the format of the file, so rather than simply using File | Open, use File | Import | Raw Data.
There you will need to change the Encoding to U-Law and the sample rate to 8000.
At that point, you should have the file open, and be able to play or modify it to your liking.
When you are happy with the modifications, rather than simply saving, you will need to use the File | Export menu option.
When prompted with the Export File dialog box, enter a file name and location for your modified ringtone. The Save as type should be Other Uncompressed files. Then click the Options button.
When prompted with the Specify Uncompressed Options dialog, set the header to RAW and the Encoding to U-Law. Click OK and Save.
You now have a new ringtone that can be uploaded to your CUCM server(s).