iPhone won't ring, only vibrates I have my iPhone5 set on "Vibrate on Ring"  and the volume is not on mute, but when someone calls, it only vibrates. I've included it in Notifications Center, but that doesn't seem to do anything. Do Not Disturb has also been turned off. 
How do I fix this?
I assume that you have checked that the hardware switch on the side of the phone isn't set to silent?

Right near the volume buttons is a switch, if it shows red then your phone is on silent, flick it up and the phone is no longer on silent.