Green dot of FaceTime on

Hi arpana241,

Thanks for coming to Apple Support Communities for help today.

This page will explain the green and orange indicators you may see: About the orange and green indicators in your iPhone status bar.

Closing the FaceTime app may resolve this: Close an app on your iPhone or iPod touch

"iPhone X and later

1. From the Home Screen, swipe up from the bottom of the screen and pause in the middle of the screen.
2. Swipe right or left to find the app that you want to close. 
3. Swipe up on the app's preview to close the app."

You can also Restart your iPhone.

Let us know more details if FaceTime is still active after this or your audio is still disabled.

Have a fantastic day!