Hi there, 1. Connect your Bluetooth headphones to your phone. 2. Open the Phone app. 3. Make a call or answer an incoming call. 4. Once the call is connected, tap on the three-dot menu icon in the top-right corner of the screen. 5. Select "Settings" from the dropdown menu. 6. Scroll down and look for the "Audio" or "Call audio" section. 7. Here you should see an option to "Use phone's audio" or "Use phone's microphone". Tap on this option to switch to the phone's microphone.