Weird Circle in status bar while using phone

[clerk]

Ok. Help me out here. I was on the phone and a tiny grey circle appeared in the status bar to the right of the camera. It constantly flickered and seems to fluctuate based on the voice output of the person on the other end.

It went away when the call dropped. Normal? Is that the speaker or something? Never seen that before.

 

[Javier P]

That's probably the proximity sensor.

 

[Hermes Hidayat]

Ok. Help me out here. I was on the phone and a tiny grey circle appeared in the status bar to the right of the camera. It constantly flickered and seems to fluctuate based on the voice output of the person on the other end.

It went away when the call dropped. Normal? Is that the speaker or something? Never seen that before.

Its the proximity sensor if im not mistaken.