As for me, it's almost never a good time to take the phone, I'm usually quite busy - working, playing with the kids, helping the kids with things, visiting the loo, running to catch some metro (and I do think it's rather rude to talk in the phone while being on the metro), in the middle of some gluing or painting project on the boat - hence I hate it when people aren't quick on the phone. I don't think it's rude at all to say "sorry, but I'm very busy at the moment", or "sorry, but I can't talk right now".

It seems like my wife has another opinion on that, if her friend calls her, I know I've "lost" her for at least half an hour.

There is a telecom here with the name "TalkMore", I wish we had one with the name "TalkLess". :-)