This is the software publisher's description.

Turn any WAV, WMA, MP3 or M4A audio file into your own custom ringtone - all for free! With its simple interface, ToneShop can help you make your own ringtones down to the millisecond and even preview your ringtones.

All you do is choose the ringtone format you want your ringtone file to be in, load in your original audio file and choose a save filename and location. Next, you use the play controls to listen to your audio file and locate the portion you want to become the ringtone. You can use the trackbar slider at any time to navigate through your audio file.

When you think you’ve found the starting position for your ringtone, press the Start button and the exact starting time down to the millisecond will appear in the box next to it. Do likewise with the Finish button when you think you’ve found the end. Now, press the Preview button to hear how your ringtone will sound. At this point, you can now manually edit the Start and Finish times by clicking in the text box and type in new values. However, make sure you stick to numbers only!

Once you’re happy with how your ringtone sounds, press the Convert button and ToneShop will do the rest. After it has completed the conversion, just transfer the ringtone file to your phone and activate it as the new ringtone and you’re done.