Clamshell?
I rarely make or receive phone calls on my Galaxy S5 but when I do I really struggle with the microphone. Other end can rarely hear me. I assume this is because the microphone is behind the pinhole at the bottom, not helped by the soft case, and the tiny speakers are at the back.
What would be nice would be a phone with a decent sized microphone and speakers. Clamshell so the speakers are by the ear and the microphone folds round to be near the mouth. [No I don't want to carry round a headset just for the couple of times a month I may need to make a call.] Bigger speakers and microphone don't play well with the screen side nor with the edges of ever thinner cases. How about a phone which folds backwards so you can hold the speaker and microphone on the back of the case next to your ear and mouth? Just like a real phone.