Agitozecter

I've had an A900, with Sprint as a provider, for a couple of months now, and I'm kind of miffed at the fact that you can't upload your own ringtones to it. I'm pretty sure that Sprint has regulated the phone so that customers can't do what I want to, but my alternative (their stores) don't have the ringtones that I want to use. So I was wondering if anybody knows how to or actually have gotten around to being able to putting his or her own ringtone on. If you were able to, what software did you use? Was it free? Was it downloadable? If it wasn't downloaded, where were you able to find it? I appreciate any help. :)