[Noted Nine]

Have a dual sim Note 9, 6 GB/128 GB variant, Sim Free.

Around a week ago started having call issues whereby the other party calling can't hear me but I can hear perfectly well. Once this started happening, it was most of the time, but strangely not always. Every once in a while, a call would come through with no issues.

Happens on both lines on the phone, thus ruling out it's a problem tied to any one specific sim card/ network.
Curiously however, if I'm the one initiating the call, pretty much 99% of the time, calls aren't affected by the same problem - both parties can hear perfectly.

Having done everything I know: cleared cache partition, soft reset, restarted the phone etc. with no luck, stumbled on an additional oddity- if I switch a call from the handset to the speaker phone, then back to the handset once I've received the call, it ensures a trouble free connection - other party hears just fine.

I make calls off WhatsApp rather regularly, probably even more than I do network calls, and don't experience the same issue.

Exasperated, took my device into an authorised Samsung care centre, and they said it was the hardware and they'd need to replace the mic.
Not a problem as the phone is still under warranty, but balked at the idea of leaving my phone for the required five working days for the part to be ordered and fixed.
Rely on my phone for work, and I'm frankly not too convinced they know what they're on about. The customer service guy even suggesting I was experiencing no issues with WhatsApp because it uses a different set of protocols to network calls. Something about using the speaker phone rather than the phones mic. Found that odd and goofy, but hey, what do I know. He might be right, and I might just be a little too preoccupied with my frustrations to be thinking clearly.

Decided not to leave the phone, and while researching my problem, come across a number of threads where other Samsung users complained of the same thing happening to them after a recent update.

Strongly feel its a software problem rather than hardware issue myself, and want to explore along those lines a little more before committing to having my phones innards disrupted and gutted. Something tells me very little good will come of that last scenario in the long term.

By the way, just jumped on One UI 2.5 within the last month, shortly before the phone started misbehaving. Coincidentally recieved a further 1st November, 2020 update yesterday on getting back from Samsung which had "stability improvements", and which I hoped might fix the problem, but sadly didn't.

At my wits end and would greatly appreciate suggestions for a fix and/ or learning if anyone else has had similar issues.

Further info: No I haven't dropped my phone, its in pristine condition, resides in a Spigen case and has never been in water.
I have not done a factory reset, but have bought a memory card to back up my phone in its entirety, in the eventuality I'll be forced into doing so.
Saving that as a last resort as there's no guarantee that particular measure might work.

Saw a YouTube video where someone with the identical problem on a Note 8 used a bent out of shape staple pin to poke a few times through the mic. Lots of comments with people professing how it worked and solved their problem. I'll wait to make this a last last resort. Somehow think a pin poke too far might do more harm than good.

Finally, apologise for the War and Peace length of this. Well done you for getting through it. Needed to try to get all the facts on here in order to try to find a solution.

Many many thanks in advance.

[B. Diddy]

Does this also happen in Safe Mode? https://www.t-mobile.com/support/dev...g-galaxy-note9

[Noted Nine]

Does this also happen in Safe Mode? https://www.t-mobile.com/support/dev...g-galaxy-note9

Forgot to mention. Yes it does.

[B. Diddy]

Hey @mustang7757, what do you think -- maybe try reflashing the firmware?

[mustang7757]

I recommend going into samsung members app and it has a diagnostic page there to test hardware like speaker phone , earpiece , etc and see what happens from there. Can flash the firmware again but let's use that as a last resort. Also try cleaning the mics on the phone , another would be 1 sim at a time in both slits instead of 2 sims if you have both slots taken.

[Noted Nine]

Happy to report what seems like a fix: Turns out there was nothing to do but to act on that last resort - a factory reset, and hey presto, phone working as it should.
Still rather shocked Samsung were convinced digging into it and changing what turns out was a fully functional component, rather than choosing to re-flash the firmware (as helpfully suggested here), or to factory reset the device was the way to go.
Ah well, all's well that ends well...
Hopefully won't have to deal with the issue again.
Thanks to everyone here for taking the time to make suggestions. Very much appreciated.

[B. Diddy]

Glad to hear it's working again! I had thought you already tried a factory reset, but upon re-reading your post, I see now that you mentioned only "soft reset," which I assume means a reboot?

[Noted Nine]

Glad to hear it's working again! I had thought you already tried a factory reset, but upon re-reading your post, I see now that you mentioned only "soft reset," which I assume means a reboot?

Thank you and basically, yes.
The objective was to try to solve the issue without having to do a factory reset, then go through the hassle of setting it up from scratch again. Rather tiresome getting a phone the way you want/need to use it. However, just happy to have it functioning properly again.

[Noted Nine]

An update just in case someone is following this thread and has the same problem:
The issue happened once more in the course of setting up the phone.
This morning decided to change my alarm tone and enabled the Bixby alarm - it's the set up I had before. Not entirely sure why as I'm not the biggest Bixby fan, but I also decided to activate Bixby assistant voice wake up. Again, that's how the phone was set up previously.
Deleted an app I never ever use (Vimeo) which apparently came factory preinstalled, and phone asked for me to update YouTube which I did. A call came through and bam! Once more I couldn't be heard.

Trying my best not to freak out, decided to do the logical thing and retrace my steps by undoing all my morning tinkering.
Uninstalled the YouTube update, reinstalled Vimeo, undid the activation of Bixby assistant voice wake up which I thought was likely to be the culprit. It was!
Called through on another line and I was audible once more. Toggle Bixby voice assistant back on, and I wasn't. Did this more than a few times with the same result.
There must obviously be a conflict causing the issue, reconfirming that it is indeed software related.
It's a no brainer, Bixby has been binned!!! Good riddance to bad rubbish!
Will update if anything else of note comes up.