I looked on youtube, articles, followed instruction of doing the winterboard method or the UISounds method. Change to .aiff than sms-received1.caf. Changed file replaced it. Doesn't work I'm running on OS 4.0.1, anyone know why it doesnt work? EDIT: What's funny is that I even copy the SMS-received1-6.caf to my computer and played them, they sound different than they do on the iPhone when I played it. They're two different tones.