Hey Guys, Maybe I should post this in the iPHone 6S thread too. After updating to iOS 10, I find that non OEM screens are not working on iPhone 6S. This could be related here if the replacement you're using for the iPHone 7 is non OEM. I think Apple has added a new 'security' measure.
Hey buddy, I am an iPhone repair tech. The mic for loadspeaker situations like skype, recording video, and speaker phone, is located in the same area as the ear speaker. If your screen has been replaced before on the iPhone 6, it may not have been lined up correctly. It's a very small whole left of the proximity sensor is the screen is faced down. The solution is to make sure the whole is in line, and that the 4 gold contacts on the ear speaker are making contact with the 4 gold contacts on the Front Camera/ear speaker flex cable. If that doesnt work, the flex cable needs replacing. If the sounds going through to the other person is just faint but coming through then it defiantly is just mic whole position.. The flex cable may have been cut or bent to harshly too. iPhoneDocNYC.com I'll answer any questions..