Apple is aware of a problem in which the microphone will stop working on iPhone 7 and 7 Plus models running iOS 11.3 or later, AppleInsider can confirm.
Affected phones may prevent owners from being heard in FaceTime or conventional phone calls after upgrading to iOS 11.3, or using speakerphone functions. It's an "extremely rare problem, with a need for repair being rarer still," a source told AppleInsider.
According to an internal document sent to authorized service providers, seen by MacRumors, repair technicians should be asking customers to disconnect any audio accessories, then running diagnostics if the problem persists. "Device could not detect dock" or "accessory not supported" messages will pop up for affected iPhones, at which point repairs can be made.
Crucially, in the case of this specific issue, Apple is reportedly allowing providers to request coverage exceptions for customers who are otherwise out of warranty.
The association with iOS suggests a software glitch, but possibly one breaking hardware or triggering compatibility conflicts, given that Apple is suggesting repairs.
People who think their iPhone is suffering from the problem should book a Genius Bar appointment at an Apple store, talk to an authorized servicer, or contact Apple's online support.