I hadnt made many phone calls on my iphone 4 until today, but ive now had 2 separate people say i sound very echoy and distant on the iphone. One described it as if i was on a boat in high winds running back away and towards the phone the whole time. Voice memos also have a lot of background crackle and static. Is this a common iphone 4 problem? Should i ring apple or my carrier (o2)?