Apple is circulating an internal document to its authorized service providers acknowledging a microphone issue affecting certain iPhone 7 and iPhone 7 Plus units running iOS 11.3 or later. iPhone 7 owners facing the issue might not be heard during phone calls or FaceTime chats. They may also see a grayed out speaker button during a call.
The support document recommends service providers to instruct customers to first disconnect any Bluetooth device connected to their iPhone 7 or iPhone 7 Plus. If that does not help and the speaker button remains grayed out during calls, service providers can run audio diagnostics on the handset, with an iPhone 7 with a faulty microphone throwing a “device could not detect dock” or “accessory not supported’ alert. In such cases, the service provider will have to initiate a repair request for the device. And if the device is out of warranty, they can create an exception for this issue, with the device likely being repaired for free.
While the issue first started appearing after the iOS 11.3 update, it seems to be a hardware issue as Apple’s support document does not mention the faulty microphones being fixed through a future software update. The internal document does not clearly state if the issue is with the software or hardware.
If you own an iPhone 7 or iPhone 7 Plus whose microphone started developing some issues, you can try restarting your phone and then disconnect it to all connected Bluetooth devices to see if that solves the issue or not. If that does not work, you should take it to your nearest Apple authorized service center for a repair irrespective of its warranty status.
Given that Apple has not publicly acknowledged the issue, your nearest Apple service center might not be aware of it as well. It is recommended that you wait for a week or two before you take your iPhone 7 to them to ensure they have received the internal document informing them of this problem.
Have you noticed any issues with the microphone on your iPhone 7 or iPhone 7 Plus post the iOS 11.3 update?