Anyone who knows me knows that I've been having issues with my phone for a good while now. It's an iPhone 3GS. The little switch that controls silent/ring mode is broken, when you switch to silent it vibrates once to let you know. Because this switch is broken, the phone will vibrate repeatedly when there is nothing touching it until you hit it off something or switch it to loud for a while.
Because it's an old model, it doesn't support the new iOS 7 which most of my apps have been updated