Many times when the caller on the other end can hear you somewhat, then it's simply an issue with a clogged microphone inlet. If you know where your mic inlet is, it should be a small hole, usually in the very bottom edge of a phone or somewhere near where the bottom of the keypad or touchscreen is. Many times dirt, debris and even chapstick or any number of unmentionable substances can become lodged in the microphone inlet, causing a physical barrier to your voice getting to the mic. Simply take a toothbrush (that's not being used for brushing teeth or that's not going to be further used for teeth) and dab a small amount of 91% rubbing (isopropyl) alcohol on it and gently brush over this mic inlet to clean any debris from this hole. Rubbing alcohol comes in several different concentrations, 91% is the purest and anything less than that runs the risk of causing liquid damage, whereas 91% alcohol can actually be used to remove slight liquid damage in the form of corrosion from a circuit board, but that's an entirely different post. It is best to hole the phone so that the mic inlet is facing down so that anything that may fall out of the inlet will fall out of the phone, rather than inside of the phone. Ideally, you'll want to let your phone dry fully before using it. Being that you're using isopropyl alcohol, it typically dries quickly with just some slight air pressure from blowing on it or use a hair drier on low setting and keep about six inches from the phone. Be sure not to smother the phone in alcohol as this may cause a damaged LCD if the rubbing alcohol gets behind the LCD, it can ruin it. Only the slightest amount of alcohol needs to be used on the bristles of the brush.
