Generally, people that call and leave messages are more likely to be ideal customers of your business. Your voicemail message is often not much more than a formality to the person calling.
Responding to voicemails is time-consuming. Fortunately, with the right greeting, you might be able to save yourself some hassle. If you don’t have an auto attendant, you can give callers the information they are looking for with your voicemail greeting. Of course, this means that your greeting may be a little lengthy, but that can work in your favor as callers will only stay on the line to leave a message if they still need assistance.

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.
If your business is closing on one of its normal operating days for a holiday, or is dealing with an emergency or unforseen situation, you should update your after hours announcement to avoid confusion.