Start with the right checks.
A connected headset is not always the microphone Teams is using. Start with one device and test it before changing anything else.
What to do next.
Check the headset’s physical mute button and the Mic control in Teams. Unmute only when you are ready to speak.
In the meeting, open the arrow beside Mic, then More audio settings. Select the microphone you intend to use.
On Windows 11, open Start > Settings > Privacy & security > Microphone. Check access for the relevant app or desktop apps. Ask your administrator if a setting is managed.
Before the next meeting, use Teams Settings > Devices > Make a test call if available. This option is not available in Teams on the web.
Check the result.
Confirm another participant can hear a short sentence clearly. If a test call is available, listen to its playback.
Stop and get help if…
The microphone is missing from the device list, access is managed, or the problem happens in every app. Note the headset model and exact message for support.