Could that indicator be for Bluetooth? That would make sense, because you say you have to have Bluetooth on to get audio. Could your phone have become accidentally tethered to another Bluetooth device, or tried to hook up, and keeps trying?

Have you gone into the bluetooth menu for your phone and checked things out? See if there is some new connection, or if it somehow set to keep trying to find a bluetooth connection.

As of this morning, I have a new indicator icon on my Eternity at the top of the screen. It is a white box with what looks like a MS Excell grid inside it. Since that icon has appeared I cannot get any audio in or out in a call unless I have my bluetooth on. I have been in contact with Samsung service and they have no idea what the icon is. Did a hard reset and still no luck. Has anyone seen this before? The icon and the problem may or may not be related but either way I am guessing I turned something on or off by mistake but have no idea.