Can’t hear caller
iPhone 6s Plus phone is almost 4 days old , can barely hear person on other line on phone call
Question marked as
Apple no longer sells the iPhone 6s Plus, so I'm not sure where you purchased a new one. However, you can take a look at this support document for some troubleshooting tips. If you can't hear a person on a call or voicemail or if the sound isn't clear on your iPhone - Apple Support
You also may wish to turn up the volume on the phone while in the phone call. That is the only time that you can adjust the volume in a phone call.