Hi, I've had the exact same problem. It has happened to me twice now (I am also on PS3). All my friends are in my PSN friends list and were a part of my fireteam. We all had fully functioning mics and no one was on mute. We checked in game settings as well as our PS3's settings with to avail. The first time was the same as described by Smokelaganj The second time there was just a friend and I in the fireteam. Both mic symbol were displayed however neither of us could hear the other. I have seen this issue popping up everywhere throughout multiple forums across multiple consoles but seems to be mostly on PS3. So far I havn't found a fix for this other than turning off or quitting game then hoping that the issue doesn't repeat itself.