at&t lg v20 not heard answering calls

[ChiefWilNel]

My wife has a LG V20 and she said other people cannot hear her when she answers phone. She took it to at&t store and they said the microphone was going bad. I can hear her just fine on Facebook messenger. I am deployed to Kuwait so it will be a while before I can sort it out. is this common for bad mics? I did have her check to see if the tty was off and it was. I might have my father in law do a factory reset. what else do you guys suggest to check?