Do you have a land line telephone? There's at least a moderately good chance that you don't.
If you do still have one, you likely know somebody who has opted to ditch their land line and handle everything with their cell phone. When they fill out forms for flights or online orders, they simply put the same number twice under "Home Phone" and "Cell Phone."
Imagine the surprise to a college freshman, in 2013, who comes to learn that they will still have an old-fashioned land line phone in their dorm room. Imagine how seldom it is used.