When I'm working on a task - no matter how minor - and I'm interrupted, I get peeved. Which causes me a lot of internal stress. Which peeves me further.
On the very short list of things I can control there is the telephone. So, I did some digging and found the code to stop my home phone from ringing. At all. Ever. My family, friends and creditors all have my cell phone. Charities, politicians and other people who just want, want, want...don't.
I'm amazed how productive and relaxed I am without the phone ringing all day.