At this time, the only way to use custom ringtones on the Apple iPhone is through a somewhat complicated hack.
Apple is rumored to be planning custom ringontes for a coming update to the iPhone.
iPod + iTunes
Will I be able to use iTunes music for my ring tones?
By root - Published January 16th 2007 - 21:06 in iPod + iTunes
• Sounds and Ringtones
Will I be able to download iTunes directly to my phone?
By root - Published January 16th 2007 - 21:04 in iPod + iTunes
No, not when the iPhone is released anyway. This is most likely because Cingular fears possible bandwidth issues. An Apple spokesperson suggested that it would be technically possible to add the iTunes software in the future. It is not known at this time if first generation iPhones will be able to be updated with the iTunes software or if it will be a nextgen addition.
