iOS 12 problem. On a phone call, after a few minutes the volume drops until I can't hear the other party. When I call back the volume goes back to normal. Happens with several numbers, so it's on my end not theirs. New iPhone XS. Any help appreciated.
My son just complained of something very similar to this happening on my wife’s iPhone X before. I thought he just must have been leaning on, or fussing with, the buttons. Guess not!