If you are using a laptop or PC with Realtek audio system and a 2-into-1 combined headphone/microphone/headset 3.5mm jack the system does not auto-detect what kind of device you have plugged in and you need to tell the system what kind of device you are using the jack for. In my case the very first time I plugged audio headphones into my laptop a pop-up box from Realtek HD Audio Manager asked me what kind of device I have plugged in and I checked “headphones” plus “Don’t ask me again” and forgot all about it. Two years later when I plugged in a headset with inline mic and tried to use it for video calls the mic would not work and I searched dozens of help threads and was amazed at the plethora of complicated BS answers given by “webxperts” including re-installs and registry fixes. Eventually I found the very simple answer is to go back to that pop-up box and instruct Realtek that I have now plugged in a headset instead of headphones. This headset setting then over-rides the laptop’s inbuilt mic whenever the headset is plugged in and prioritises the headset mic. So where can we find that pesky little pop-up box to change the setting again after having banished it by checking “Don’t ask me again”? Simply run the Realtek HD Audio Manager which you will find in Program Files/Realtek/Audio/HDA and double click on RAVCpl64.exe then look for a file folder icon (on my laptop it’s on the right side panel near “Analog” selector) and open the folder to find “Connector settings” and check the option for “Enable auto-popup dialog, when device has been plugged in” and click OK. Do this with your headset plugged OUT and then next time you plug it IN the dialog should pop up and you can select “Headset” instead of “Headphones” and maybe this time don’t select “Don’t ask me again” if you plan to keep using different devices in this jack.[br]
If this doesn’t work for you the first time try re-starting your machine after changing the setting.