Funny you would bring this up. I've caught myself doing this quite a bit and have tried to stop doing it with mixed results. I don't know when it started.

Mt Mom almost never says goodbye, she just hangs up. Then again she almost never says hello when she calls me just an " Oh, Jill" like she's surprised I answer my own phone?!

I personally think it's kind of rude not to say goodbye and if I'm calling somewhere to ask them a question I always thank them at the end.

SM, when I ask someone on a call line how there day is going, I'm actually curious or hoping to brighten their day a little. Sometimes I even ask them where they are located or how the weather is where they are.

Well, I'll amend my previous remarks and saying it is rude to hang up if it isn't obvious the talking is done now.

So for me it might be:

<ring>
<phone picks up>
Hey John, quick question. Do you know X?
Sure, answer is Y.
Thanks.
<phone hangs up>

So, in my opinion that had the indicators that talking is done. But I never said a verbal equivalent of "ok, we're going to hang up now. No, you go first! No, I went first last time, you hang up first this time. Ok, on three! 1, 2, 3 ... you didn't hang up!"

If it's absolutely clear that the conversation is over, I can live with just hanging up. It's really the awkward silence that bugs the crap out of me. (Cutting someone off is just plain rude, I think everyone agrees with that.)

Err, Szczerbiak, can you account for your whereabouts on Sept 13 last year?

Man killed for not saying "Bye"