I often see people with their headphones/earpiece plugged into the phone, holding the phone in one hand and holding the microphone on the headphones to their mouth with the other. I always feel like saying “here you go mate, let me show you something…”
There are, very rare occasions, when I get a call while I’ve got the ‘phones in listening to music, and reading a book, so I’ll continue to hold the phone while I take the call, and it does allow me to switch to another screen during the conversation, if necessary.
I’ll also hold the mike/remote a bit closer to my mouth to avoid being drowned out by background noise if I’m outdoors, my hands free headset is, after all, only a few centimetres away from my mouth, plus it avoids added microphony due to the cable and remote rubbing against my clothing if I move.
Same if I’m using the hands free BT headset, I frequently have to use the keyboard during a call, so holding the phone is logical, allowing the use of the keyboard or searching the calendar during the call, or whatever.
Not while driving, of course!