For some odd reason, my iPhone 4 doesn't ring/vibrate when a new text comes in. This doesn't happen very often but it does happen couple times a day. Which is weird. Anyway, I normally have my iPhone set on silent, so it's just the vibration, and like I already said, it doesn't always vibrate. But then I switched it from that to the ring/vibrate mode and it still doesn't always vibrate and ring. Anyone else having this issue? Is there a way to fix it?