I Have an iPhone 6 that when its on speaker people can hear me but when I take it off speaker and put it to my ear they can not hear me. I have done complete erase and are on 9.3.1. Anyone have an ideas talking on speaker is getting really annoying
Did you already try the troubleshooting in this article?
Get help with the microphones on your iPhone, iPad, and iPod touch - Apple Support
If yes, and the microphone still does not work as expected, contact Apple to get it serviced, or visit an Apple Authorized Service Provider next to your place.
iPhone - Contact Support - Apple Support
Mic does not work when not on speaker
