A while back there was a thread in one of the HN comments where multiple people expressed anxiety about answering a phone call to them with, "hello?" Preferring to instead let the other person speak first. Which is exactly backwards of the established social etiquette of phone calls ever since the telephone was invented. I don't know where we're headed where social norms and tech are concerned, but it's sure to be interesting at the very least.
I think the "long-running" part is important. Like, if I'm doing pair programming with someone one else for a bit, and then we settle into a mode where we're both working on our individual parts, and then all the sudden we hear a third voice in the call from a person who just joined -- it does seem out of nowhere, and kind of discombobulating if there's no warning.
