The phone on the table also speaks

Leaving your phone on the table seems harmless. You're not using it, it's on silent. But it's there, and you both know it: at any moment it could buzz and take the attention that the person in front of you has right now. Besides, attention divides worse than we think. Even if you don't look at it, part of you is waiting for it to buzz, and the other person notices it in how you listen. Putting it in your pocket or leaving it in another room is a small gesture that says something big: right now, you come first. There's no need to announce it. The other person notices.