I have the exact same problem, started a week ago today. Voice memos shows the same message as you, calls don’t work, Siri doesn’t work, and videos have no sound. I know a friend with the same problem on her iPhone 7. Back in May IPhone 7s and 7 plus’s were having the same issue, and Apple issued a recall with a free fix, even without a warrenty. But from an article I found of reports like us of the problem still being an issue with iPhone 7’s, Apple is refusing to acknowledge the fact that it it’s still a problem. They’re forcing people to pay $300 for a problem they created!!!!! It’s not our fault. Also, from what I can tell the issue started popping up on the same day or two, me and my friend both had ours start on Monday. I really wish Apple would do something, because what’s the point of me having a phone if I can’t even call, might as well be an iPod! Anyway, I don’t think there’s a fix for it besides paying $300+ to Apple. At least you’re not alone :(