Thought of the day - office phone, why?

It dawned on me today that 99.9% of the time, when my office phone rings the person on the other end of the line wants to sell me something. At first this was annoying, but now I realize - this is great. I automatically know what I am in for when I say hello. THe implication of course, is that people I already have a business relationship with - either contact me via cell phone, email or IM. Of course, this also begs the question - why do I even have an office phone...