Half-listening to a friend while you text someone else is double-booking a person.

Attention cannot really be split, it can only alternate fast, and the person across from you can tell. They watch you arrive back in the conversation half a beat late, and they start editing what they were going to say, usually shortening it. Nothing has to be said for the message to land. Being handed part of somebody is worse than being asked to wait.

When a friend starts talking about something real, put the phone where you cannot see the screen. If you truly need to answer, say so out loud and then do it. Come back and ask them to finish the part you cut off.