Pay attention to the person who’s talking.
Sit up, shut up (your electronics), turn your chair and actually face them. Make eye contact. Not the stalker kind of eye-contact, but enough so they know you’re paying attention to them.
Don’t believe it’s that simple? Next time you’re in a meeting, take a look around at who’s paying attention or not. Not just turning their head, but actually turning their entire body and facing the speaker. Now compare that to somebody who’s merely turning their head. While this is better than not paying attention at all, just turning your head gives off the body language “I’m better than you” message.
Try it and see what difference it makes in the follow-up relationships you have with the people you meet with regularly.