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.
Recording voicemail greetings for your business or personal life requires a separate list of priorities, because they are being used for two distinct purposes and will be heard by two very different types of callers. I have a friend with two cell phones - one for work, and one for personal calls - and if you call both lines, you would never know it's the same person.

The attendant menu for your main contact number may be the first form of contact that a customer has with your business. Make sure your greeting is clearly articulated. Provide an option to speak with an operator if the caller has a question that is not addressed by the menu options.
28. Hey, there. You’ve reached [your name]. Please leave me a brief message about the reason you are calling and your contact information. I will call you right back at the earliest opportunity. Have a nice day!