microphone doesn't work after download of backup

Can anyone help me with microphone problems after downloading my backup on to a brand new iPhone 7?

I upgraded from an iPhone 5c to a brand new iPhone 7 and when I make or receive phone calls those on the other end of the call say they can't hear me or it sounds like the connection is bad or my voice keeps cutting in and out. While I can hear them perfectly.

I have spent hours on the phone with Apple Tech Support and even had a replacement phone sent to me, but as soon as I download the backup it starts again. They have had me reset to factory settings using two different methods and set it up "as a new phone" without retrieving my iCloud backup and the phone works fine for days, but as soon as I reset it to retrieve my contacts and other info from the backup this problem begins to happen again immediately.

Any suggestions??