IPHONE

In addition to the above correct info—you’ll need to have a microphone active for the iPhone to “listen” to what you say on the call in order to transmit that over to the speaker on the phone on the far end of the call, for instance—here are most of the other indicators and icons used by iPhone: Status icons and symbols on your iPhone - Apple Support

The microphone-active icon is usually 🟠, though it’ll switch to and show as 🔴 on some backgrounds. This where the 🟠 icon won’t show up as well.

That the microphone is in use does not mean you are recording, only that an app is using the microphone. What that app might do with the audio data gathered from the microphone is entirely separate. The voice recorder app will, for instance, record. The phone app doesn’t, though the person you’ve called might.

The mic is in use.

Hi, it means your microphone is active in the background. It’s new security feature of iOS 14. Also if you see a green dot it means that the camera is active in the background.