My boyfriend has a the Thunderbolt for about a month. When he calls my work number (I work for Verizon, in a Verizon owned building) we can talk for a few minutes then the sound goes out on his end. I can hear him talking, but he can't hear me. Sometimes the sound picks back up after a few seconds, sometimes its minutes. We've taken it into an experience store. They can't find a problem. He knows he's not muting it because I wouldn't be able to hear him if he was. It even happens when he has the speakerphone on. This happens to one other person he calls. But that person is using a HTC Sense(?) on Sprint. Has anyone else encountered this problem?