mic very low sensitivity during calls, works as normal in other apps

I've had the phone about 1.5 years. I bought it new, but it was virtually brand new at the time. Right now when I make calls I cannot be heard unless I speak directly into the mic or very loudly, if I get too close it sounds distorted (as it should).
I can record voice memos in multiple apps, and i have made calls using facebook messenger with no problems.
I can make calls without issue using a bluetooth headset. Placing calls while Speaker phone does not help.
I have done a factory reset of the phone and operated in safe mode.
I have turned off "Noise Suppresion" and "Voice Clarity" and tried having one or the other on as well.
Most of my tests were conducted by calling my voice mail and trying to change my greeting. Other tests were conducted phoning my wife's phone.

I feel there must be something wrong with proprietary software related to making calls? I was considering rooting the phone and removing the call App then restoring it, however, I have little experience fooling around with phone software.

any help would be appreciated.

Welcome to Android Central! Which phone? Are you saying speakerphone calls also don't pick up your voice well? If speakerphone calls also go through well, then it's probably an issue with the primary phone mic (which could be blocked, like by a case or clogged with lint, or it could be faulty). Voice recorders and other apps that use the mic often use the secondary mic (at the top of the phone), so it could still be an isolated issue with the primary mic.

Ha! sorry! forgot the most important part! It's an LG G6.
When I make calls on speakerphone I have the same problem with the microphone; there is no sound/voice getting through o the other end unless I put my mouth right up on the mic, or yell.

I didn't realize there were possibly 2 microphones, big oversight on my part. Looking now, there is a little hole on top near the headphone jack. Not sure if it's a mic.

Thanks for the reply

The phone mic is on the bottom of the phone. The general mic (including speakerphone) is on the top of the phone. (Page 28 in the manual.)

The general mice sensitivity is adjustable for voice recording and other apps, but neither one is adjustable for phone calls (it has to do with legal restrictions on the transmitted bandwidth of the phone signal).

Does this also happen in Safe Mode? https://support.t-mobile.com/docs/DOC-34097

yes, same thing in safe mode.

seems like the main mic on the bottom must be physically clogged. I think the safest way to do this is to probably open it up and take a look, I don't want to stick anything in the mic to try and unclog it and possibly make it worse, or ruin the mic.

I've already stripped this thing down to the battery before, so I know how, although it is a PITA.

Thanks for all your help.

I would have originally thought the primary phone mic on the bottom of the phone was clogged, but this shouldn't affect your voice when using speakerphone, since that uses the secondary mic at the top of the phone.

OK. Pulled it all apart this weekend, found there was some gunk on the inner mic corridor. That opening is much larger so I was able to scrap it out with a sim card tray pin. The "gunk" seemed like adhesive tape that had broken down? anyway, the mic seems to work now. Right before I fixed it, however, I started having consistent crashes and boot loop problems...lol. Time for another thread i guess.