So, all a ringtone for an iPhone is is an AAC file (.M4A extension). Keep this in mind, your ringtone cannot exceed 30 seconds (well, there is a way to do it, but it won’t play more than 30 seconds since your caller goes to voicemail after 30.) Open iTunes, be sure that your import format is AAC (in OSX, Preferences -> General -> Import Settings -> AAC.) Locate your song in your library. Now here’s the fun part, figuring out which 30 seconds (or less) to use. Find your starting point and note the time (IE, 1:30 into song etc…) then your end point (again, 30 seconds from start point max.) Bring up the properties for that song (COMMAND+I on OSX) and goto the “options” and set your start / stop times. Play the song and see if you like your settings. TIP – you can use 1/2 seconds; IE 1:30.5 … If you like it, right client and select “Create AAC version”, then right click that newly created version and select “Show in Folder”. Copy that file to your desktop and rename it from .M4A to .M4R. You can delete the file in itunes and remove it as long as you left the .M4R file on your desktop. Now, drag the .M4R file into iTunes and look under “Tones” … VIOLA!