A professional voicemail greeting should be no longer than 60 seconds. List the important information we've discussed above, provide alternative methods of communication and close with a thank you.
31. Hi, this is [your name] at [your company]. If you are calling for [include reason] please visit our [website, social media handle, etc.], contact [name and title of colleague and phone number] or send me an email at [insert email address]. For other inquiries, leave a brief message and your name and number and I will call you back by [timeframe].

Provide as much useful information in your business voicemail greeting. However, be sure to keep it short and concise. An excessively lengthy voicemail can be damaging rather than helpful. Keep your voicemail to around 20-25 seconds maximum.
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.