There is also the somewhat related problem of how to transition from pleasantries and chit-chat to the real point of the conversation when someone calls you on the phone. Sometimes people can stay in this mode for several minutes, and it's hard to convey the message "So, why are you calling me?" in language that is socially acceptable. My solution--which I believe I borrowed from Randy Pausch--is to say, in a friendly tone of voice, "What can I do for you?"