I've got a newish LG G5 here, which has been fine up until a few days ago when suddenly people started complaining they couldn't hear me on calls. When I talk into the G5, the caller on the other end hears nothing. If I literally shout into the phone they can just about hear faint snippets of speech. On my end I hear the other caller just fine. I'm also hearing a loud echo of my own voice in my ear when I speak. It happens this way around regardless of which party initiated the call. I know it's not a physical problem with the microphone itself, as I've tested both audio and video clips with the phone, and the mic is picking up sound perfectly clearly. I've Googled the issue and tried a bunch of suggested fixes, including rebooting the phone, running in safe mode, reinserting the SIM card etc. (one post mentioned something about "TTY mode", but I couldn't find a menu option for this to try it). Any ideas what might be causing this, or what else I could try to troubleshoot it?