Focus is the key for me to have things done, although I have my technique to manage my work pipeline (My Pipeline Is My Inbox) there are many distractions that prevents me to focus on my work items pipeline - phone calls, small talks, etc.
When I set time to work on something - I am completely dedicated to it, since I know if I do not finish it I will need to schedule another time slot thus postponing other work items - my productivity would suffer.
To reduce distraction I set my Outlook to offline mode, I do not answer phone calls, I do not talk to colleagues, I put earphones to create my ambient environment - usually listening to KWJZ radio.
Of course, for all voice mails I get I call back either immediately after I finish my work items or get it into my pipeline (see link above).
Such approach save a lots of distracting context switching, save time on warm up time for the topic I work and keeps me more productive