If you're interesting in improving conditions for mankind around the world, here's a quick and easy way to start: When you're leaving a voice mail, keep the message brief but give your number slowly. Over-enunciate and say it twice to be sure the person gets it.
One of the great pains of office life, I'm learning, is sitting through a 45-second rambling voice mail which concludes with, "So call me as soon as you get this, I'm at 4-5-[garbled]-2-8-[garbled]-4. Okay? Bye."
Don't be that guy.