iPhone makes shutter sound when taking photos despite being on mute I recently purchased a refurbished iPhone 6. It's been set up from my old device's iCloud backup and updated to iOS 10.2.1. 

Unfortunately, despite being set to silent via the physical mute switch, my iPhone will make a shutter sound whenever I take a photo using the built in camera. I'm using my device in the United States, so country laws shouldn't be an issue.

Why would an iPhone camera be making a shutter sound while set to silent?

Edit: Worth noting that using the mute switch worked for my last iPhone
It is possible the refurbished unit originated from Japan or Korea, where the setting of the mute switch is deliberately ignored by the Camera app. See this article at engadget.