This was posted by a Verizon Technical Support Agent on the Verizon Community Forums.
I have some good news to share about the audio going out on these devices. I did a query in our trouble ticket system about the Charge losing audio and randomly muting the call. What I found was actually surprising to me. SOME Charges were affected by network element in their market, and how the Charge responds to a switch element. Because it was so widespread, we assumed it was only a software problem (Samsung is fixing this issue as well with a software update). Here's an abbreviated resolution from one of the tickets that had this problem resolved: "There was an issue with the Samsung Charge in markets that use the Tellabs 3700 PAEC and that was resolved on Friday 8/12 BY changes on the 3700 PAEC ECANS .. Customers should be fine since then .. In MD - the issue was fixed on the night of 8/19." So many customers have already seen improvements.
So, what this means is each person that is experiencing issues with audio going out randomly while in good coverage should call tech support directly at 866-892-7957 > 1 > Enter number > Choose the option for advanced devices and PDAs. This will get you connected with tech support. If you'd like to give them a ticket to reference, use NRB ticket 4574701 as a reference. It's possible that the network your Charge is connecting to did not receive the 3700 PAEC ECANS update. If your issue is not resolvable by the NRB, it will by fixed by the Samsung software update (of course I have no ETA on that other than soon).