When someone puts me on call-waiting while they take another call, I hang up. Not long ago, I did the equivalent of this in person when interrupted in face-to-face conversations at a conference: I walked away.
Of course there are situations in which a conversation is interrupted, perhaps only briefly, and the interruption is completely inoffensive. And then there are the other cases.
In a crowded situation such as a conference or some other kind of meeting, it can be difficult to deal with conversational convergences involving various people who all have things to say or ask at the same time. But there are polite ways to deal with this and there are impolite ways to deal with this.
To this day I remain impressed with the social skills of a Famous Professor with whom I was conversing at a conference more than 2 years ago. As so often happens, another person walked up to us and started a conversation with my companion, as if I didn't exist and as if a conversation were not already in progress. The person with whom I was conversing said "I am talking with FSP right now" and dismissed the hapless social moron so that we could continue our discussion. That is a rare event.
At a meeting this spring, I experienced more typical examples of this type of interaction; in fact, more than once at the same meeting. In one case, Big Professor X walked over to me during a break in a session and said "Oh good, you're here. I've been wanting to ask you something about this research you've been doing on Z." He asked me a question and I started to answer but didn't get more than half a sentence into my answer when a man I didn't know walked over and started talking to Big Professor X. Did X inform the interrupter that he was already in the midst of a conversation? Did he say "Do you know FSP? We were just talking about Z." as a gentle way of bringing the new person into a conversation that was in progress?
No, he did not. He turned to the other guy, listened to his question, and then started to answer. That's when I walked away. He put me on hold to take another call, and I found more important things to do somewhere else. I wasn't annoyed or upset; I just saw no reason to stand there and wait for my turn to speak.
Perhaps he thinks I was rude to walk away before answering his question. Or perhaps he figured it out. Perhaps I will send Big Professor X a copy of FSP's Guide to Academic Etiquette: Special Conference Edition. He did not mean to be rude; he just didn't know what to do. He didn't think. Or maybe he has a short attention span. Or something.
And interrupters should try to learn to Start Seeing Other People when starting a conversation, or at least learn how to figure out when is a good time to jump in. There are some people who can't read social cues for reasons beyond their control, but the fact that being talked over and interrupted is a much more common problem for my women colleagues and me than it is for my male colleagues suggests that there are some issues of perception (or lack of perception, depending on your point of view) that could be improved with a bit of awareness (and a handy etiquette guide).
8 hours ago