The ringtone format that samsung phones play are .mmf files.
I will tell you how to make your own voice ringtones however before you begin you should know that your phone will not take anything larger than 50 Kb.
The programs that I use:
1. Audacity (Just type Audacity in Google, then software get display)
2. Cool Edit Pro (Same way like audacity)
3. Windows Sound Recorder
4. .Wav to SMAF converter (can be found by searching on google for "SMAF Yamaha" and it should be in the tools section of the site)
Now lets begin:
1. Just take any mp3 file that you want and open it up in Audacity and magnify the part that you want and select it. The selected part should be no longer than 10 seconds or else it will go over the maximum 40kbs. After selecting it go to file and choose save selection as .wav.
2. Open up Windows Sound Recorder and open the file then increase the volume by 50%-75% and save it.
3. Open up cool edit pro and open the file now go to edit and convert sample rate, you have to set it to 8 khz, 16 bit mono, or else the SMAF converter won't convert the file. After you're done converting go to the Noise Reduction Option and press the get profile selection button and set the Noise Reduction level to 6 and save.
4. Final step, open the SMAF converter and drag and drop the .wav file into the converter and your .mmf ringtone should appear.
I hope this helps you and I will post some of the ringtones that I made myself here.
So start R&D and let me know the result.