When you are on the phone have you ever been distracted and found yourself coming back to the conversation just as the person at the other end says something like “… don’t you agree?” or “… what do you think?”
It’s not intentional but … just as with face to face conversations … it’s harder to hear what’s being said if you can’t see the person.
My top tip for this is to focus on some inanimate object and talk to that! I usually go for a light switch or door handle. I wouldn’t opt for a photo as that is more likely to distract than help you focus and definitely nothing out of the window as the distraction possibilities are immense!
A simple light switch is all you need. Look at it as you are listening to the other person and you are much less likely to float off into a day dream.