Has anyone else experienced this? Whenever I receive an SMS my iPhone fails to alert me. If my phone is locked the screen lights up as if I were to wake it up. It shows that I have a message but obviously there is no alert. When I'm listening to music, the music dips in volume but I don't hear any SMS tone as I usually would. I've turned it off and on again and that fixed it temporarily. But I adjusted the ringer volume, only by 1 and its happened again. Turning it off and on again worked, but I altered the volume by the volume buttons when listening to music, so its not working again. Anyone else experienced this? I haven't restored my iPhone so that might fix it. I own an 8GB 3G btw.