Due to network setting issue we are not able to hear voice

So one iPhone 7 works, and another does not?

Please post the text of the “due to network settings” diagnostic or error message being shown.

Try updating your carrier settings on that iPhone, if this is an issue with cellular audio.

Manually update your carrier settings on your iPhone or iPad - Apple Support

Speaker_issue_with_netwrksetin Said:

"Due to network setting issue we are not able to hear voice: Not able hear voice on one of my iPhone 7…due to network settings…when ever we reset it works….after some time we are loose…how to fix this issue"

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Try a New Router:

If networking is the culprit in one way or another, then perhaps it is time for a new router? Contact your ISP.