Consider for a moment how your phone is currently being answered. Professional courtesy is quite often not the standard for many college students. An abrupt "Yeah!" could be listed among the more courteous greetings. The more outrageous remarks will often buy you a major black mark in the professionalism category—even if it was your roommate answering your phone and acting crazy. A simple "This is ____" is always a pleasant change for a college student call. Make the change today, before the next (or first) employer phone call. If you have a landline, you should also encourage your roommate to do the same.
The voice mails I receive in response to this greeting allow me to use my time most productively. I learn the purpose of the call and when they are available for a return call. This allows me to prioritize when I need to return calls and helps me be better prepared for the ensuing conversation.

You don't have to be a large national business to make an impression with your callers. On hold messages are ideal for SME businesses to sound just as professional.
“People often assume the voice mail lives on the phone when in fact it lives in the carrier's server. Verizon Wireless spokesman Paul Macchia said the company has a deal with CBW Productions that allows customers to save greetings or voice mails to CD, cassette, or MP3.”