All of the volumes on the iPhone are too low: speakerphone, handset volume, ringer volume and SMS/Email Notification volume. It's not the hardware, and I find it incredible that Apple could have released the iPhone with such an obvious software bug. I can't imagine that anyone at Apple testing the phone and taking it out in public before the release would not have obviously noticed that the volume is set grossly low.
Apple needs to fix this ASAP. All we can do is hope and wait.😡