I finally got to a solution for this, after trying all manner of software diagnostics that didn't work. It would appear that the only way to solve this is to replace the charging port which also houses the microphone. This sounds more onerous than it actually was.
I bought the replacement board from Amazon for app £10, including two mini screwdrivers - and then followed this tutorial on YouTube. https://youtu.be/TVJN4FYk2t8?si=pk1sdGnLxEtzGcoc
In total, it took me around 25 mins. The hardest part was getting the casing off at the start. Two things that I would suggest - that aren't mentioned on the video - that will speed things up for you, are:
Make sure that you have a very thin, hard piece of plastic, available to start getting the case off. It's shown on the video but you do really need it.
If you can, use a small magnetic screwdriver as the machine screws are very small and difficult to put back in. (Even if the magnetic screwdriver isn't the right size, it will assist you in locating the screws in the holes. Using your fingers makes it very difficult).
I'm happy that it worked first time, after the swap out. My only regret was spending so much time on trying to find a software solution.
Good luck!
This pretty much fixed mine, you can try it to see if it helps but others have said it didn't. :
Mine did this and the fix was to turn off "Turn Over To Mute". This is when it mutes your phone when you lay it face down.
!! UPDATE !!- The problem came back, so mine was only a temporary solution...
!! UPDATE 2 !!- It seems that my solution has fixed mine for the most part , now it only does it maybe once out of every 20 calls or so. And I'm not taking it apart to fix it, if it gets bad agian I'll just buy another phone...
There is one big difference between my phone and most others that have this problem, mine has never had a earphones plugged into the jack nor have I ever used a bluetooth headset of any kind. I don't know if this has anything to do with it, but thought I'd let everyone know anyways.
