Look up and say so

The second part is for the times the phone is already in your hand when someone starts talking, and for the times you catch yourself mid-glance.

The move is the look up. Phone down, on the table, on the arm of the chair, wherever it lands, and eyes to the face. Not "hang on". Not finishing the sentence you were reading. Down, and up. If the thing on the screen was mid-way, it'll be there in ten minutes, and it doesn't need you to say goodbye to it.

If you were caught, say so, once and briefly. "Sorry, go on." That's the whole sentence. Not "I was listening", which chapter 13 explained arrives after the face has already said otherwise, and which turns a small drop into an argument about whether it happened. Not an explanation of what was on the phone. "Sorry, go on" admits the glance, gives the turn back, and ends. An earlier book, You've apologised enough, is about why once is the right number.

Then there's the genuine exception, the call you're waiting for, the message that really can't wait, and the method for that is to say so before you look. "I need to check this, it's the hospital, give me a minute." Or at the start of the evening, "I'm expecting a call from the builder, so if the phone goes I'll take it." Said first, the look at the phone isn't a glance. It's an announced pause with a reason and a length, and the other person can hold the story across it, because they know what the pause is and when it ends. Said afterwards, or not at all, it's a glance with an excuse.

Naming the exception is also what keeps it an exception. If you have to say out loud "I need to check this" you'll find you can't say it for a delivery update, and the number of things that turn out to be worth saying it for is small. My guess is one or two a week. That's the real rate of the thing that can't wait, and the glance was checking for it fifty times a day.