My samsung galaxy ace had an issue for a while. every now and then the phone makes no audible ringtone when a call is coming through, the call still comes through and if i am looking at my phone i can answer it. however if it is in my pocket etc. i have no idea that it is even ringing. my phone is not on silent and the text message tone works everytime but for some reason the ringtone for calls only plays on occasion. i have tried battery pull, and changing ringtone etc but problem persists!?